So, say you're staring down 35, and for whatever reason you want to hold off on getting a longevity potion. Maybe there's a waiting list for an expert you're on, maybe you don't want to give up on having more children just yet, maybe you can't afford a very impressive one right now.
What are the alternatives, or, rather, how can you secure decent aging modifier in the interim?
-Albert
-Living Standards
-Healthy Feature (covenant boon)
-Health bonus for your Lab (again, in Covenants
-A Familiar with a really high Bronze Cord score.
I'm assuming this choice is after character creation by the way you wrote the question.
Those should get you another decade or two with just reasonable apparent aging.
Transforming Mythic Europe has a section on using magic to improve Living Condition Modifiers. Doing things like warding against vermin, magical food preservation, magical sewage systems, magical AC (as in air conditioning not arcane connection). Basically any appropriate effect of a certain Mag bumps up living conditions by a point. Be creative and try to avoid warping.
Finding a Learned Magician would help, and using+integrating their Salutem effects that improve living conditions for their target. They don't destroy fertility in the manner a longevity potion does.
My solution brings Warping... so beware.
Search for some hedge magis than brings Virtues or one Initation Cult Script - search for one adquisiton of Unaging. Magic Craft users, Gruagrachan and Learned Magician can be very usefull then. or one Eternal Life Seeker Cult (Alchemists).
I wonder if having a bed and a comfy chair of Virtue would help...
To avoid the sterility issue, you could Integrate the "Longevity Rituals don't cause sterility" virtue from Magi of Hermes(?). Which doesn't really answer your question, but I suppose it does reduce the reasons not to invest in the ritual, I suppose. 
Of course. Comfy chairs good for health, teaching, and interogations. 
Okay, so here's what I've got:
#1: Get a baker for the Covenant with puissant and affinity to run the kitchen, and get the kitchen upgraded to +3 Innovation, +3 Supplies, and +3 Tools (because you've already done this with the Covenant blacksmith and other craftsmen, so they're also managing Workshop totals of 18+, right? The goal is a free source of Flawless Equipment + Flawless Tools), so that the output of the kitchen has +3 or +4(if the baker has managed to get his Craft up to 12) on longevity for everyone in the Covenant.
#2: Get a Bed of Quality with the effect being: Affects Sleep +6, specifically adjusts sleep to be especially healthy. Get a cloth-of-gold Blanket of Quality for Health +2. Maybe even have a bed designed as a focus, then point out to the SG that it doesn't actually take up lab space, having its own dedicated space. Hope your blarney roll is good enough for to get the +8(or more) to Health, i.e. +4 for longevity. (Note that it's out of paradigm to sit down to read, and thrones don't give health bonuses.)
#3: It ought to be possible to get the bronze cord to at least +3.
#4: Using mundane alchemy if you must, arrange for durable, not-gonna-break-for-a-long-time, non-toxic piping for centralized heating/cooling, running water, and sewage lines. Use magic in the centralized locations so that they're the only part to suffer warping, and can be replaced/rebuilt every 50 years or so.
#5: Bathing-houses with stuff like mineral baths. Again, keep the magic out of the way and pipe the benefits in. Magic that does not activate often enough to warp (say, cleaning effect every so often) should be fine.
#6: Magical food-preserving room. Make sure to replace room every 50 years.
#7: Cats enspelled to be really, really good at hunting vermin. They'll die before they start getting Major flaws.
The aggregate of 4-7 ought to be at least 120 levels, so another +3 or more.
#8: If you don't have a Healthy Feature, arrange for one or more (like the bathing-houses). +1-3
#9: Have a garden built around your lab, Feng Shui'd out the wigwam for beauty and stuff. Or move your lab to a garden. Whatever. Justify it as a source of medical herbs for the Covenant. Between that, the magical superior heating you've already arranged, and, oh, let's say Spotless, you've got a Lab Health of 4, so that's another +2 longevity.
So an obsessed magus or maga should be able to get a longevity bonus of -10 or more without having to consult a hedgie or overly burden the Covenant, with that rising to about -20 in the hands of an especially persuasive player.
Hmmm . . . a lot of this sounds like stuff that Jerbiton magi would push for, since it beautifies the Covenant and helps the covenfolk(magess oblige, and all that).
Just don't make one.
Aging Penalties don't really matter until you're much older than 35. A few decreptitude points won't send you to an early grave, so just wait until you're 45 or 50 before taking your potion. Later when you are 105, it won't make much difference whether you first took your potion at 35 or 50 (indeed you'll have 15 less Warping Points if you delayed taking your potion until 50).
Initiation into Greater Faerie Blood might be an option.
Don't forget living in your lab is technically a -2 to it's modifier health.
I don't know if it's paradigm, but comfortably sitting should give you a negative impact on health and longevity:
I thought initiating (Strong) Faerie Blood was explicitly not an option, as of TMRE, p. 13, third column, first block, "Virtues Initiated"?
Merinitas initiate that, right?
They initiate you into becoming a Faerie, not Faerie blooded, IIRC.
Actually it is specifically mentioned there, I'd forgotten, I thought it was Giants Blood mentioned specifically. They actually say any virtue that is the result of "accident of birth" is off limits and we should use common sense. The reason I suggested it is because I think RoP:Faerie opens up the idea that Faerie Blood doesn't always result from lineage being kidnapped and raised by faerie and other fanciful happenings can also cause it. I know I've had characters acquire it from warping in Saga's before so at least for myself and my sagas I'd consider it for initiation.
Yes, there's some pretty good evidence from the Ancient Olympics that Pindar the Herald could give you Blood of the Gods by telling enough people you had it. The Olympic champion who have proclaimed had blood of the gods (Diagoras) even managed to pass it on to his sons, who both, in turn, became Olympic champions, and one of his grandsons too. He also seemed to develop the ability to die at will, which is interesting and possibly a form of ascension.
Actually, according to Pausanius, he had three sons and two grandsons who were champions, and his daughter was the only woman allowed to attend the event who was not the officiating priestess of Demeter, so the blood was kinda strong here...
I have a mystery cult IMS that grants faerie blood through initiation. Although this is quite explicitly a very powerful supernatural being changing your nature, rather than discovery of some form of knowledge.