Non-magus starting with Vis stock

The character in question is avaricious (minor personality flaw) with regards to vis. So, not only does he need it, he covets it, and walks a fine line between wanting to consume it and possess the vis. I don't want Personal Vis Source, because I want it to be a finite supply, something he has to seek out, not something that is off-setting.

He acquired his Hunger for Corpus Magic and lost his Gift because of a botched ritual designed to improve his Stamina. Here he is: https://forum.atlas-games.com/t/jls-companion/6755/1

The challenge I'm trying to work with is, given his avaricious nature, how much vis does he need to have on hand before finally consuming it? As he is a Failed Apprentice with a relatively decent Magic Theory of 4 (it's higher than my maga's effective Magic Theory, but that's another story) he understands the value of magus. What's a good guideline for that level? 20 pawns of vis for his horde? OR is it 10? 20 pawns means he can keep on living, as is, for 5 years. I'm also considering starting him play at Tired for Long Term Fatigue, so -3 to all actions to start.

With Peregrine's permission, I'm going to split off bps he's allowed incoming magi to bring with them above and beyond the bps he's allocated to the player to design the covenant, and give those to my companion player.