Might be doing a game day, two 3-hour sessions sort of thing, the players won't have played Fengshui before. While I know it's not the most complicated game is there any stuff that's available that can be given to the players to get them on-board with most of it quickly?
I'm also trying to figure out how easy it is to approach almost fresh - rather than having ready it first?
I've made some player and GM aids that have helped me quite a bit.
Here's a link to the thread where you can download them:
https://forum.atlas-games.com/t/homemade-fs2-supplements/10085/8
I've got a crib-sheet for common rules that fits in a GM screen or can be printed out and just used for reference. I've got sheets where you can write up all the GMCs you plan to use in a game and have them all in one place. There's also vehicle sheets where you can track the stats of vehicles AND have quick-reference to the vehicle chase and combat rules.
I've also made full-color playmats for each of the Junctures, with common rules references on them as well.
I've played a LOT of improvised sessions of Feng Shui 2, I think it works great!
I just have the players pick an archetype, give it a name and a simple melodramatic hook. I stress to them it should be SIMPLE. Trying to find the ninja who killed my master, rescue my kidnapped daughter, find the sorcerer who cursed me, get revenge on the mad scientist who made me a cyborg, etc.
Once each of the players has a hook, I put them in my brain and swirl them around and start improvising a story that will hopefully connect two or more of them together into a single session. Often I can start play with one solid idea and then figure out how to work the other hooks into it as we go along.
I generally prepare ideas for fight scenes beforehand--if you've got the "Fistful of Fight Scenes" booklet, it's great for these ideas. Another way I organize them is I'll brainstorm ideas based on the elements. For "earth", I might envision a big fight in a quarry, a mine, or on a remote mountaintop. For "fire", it might be a volcano or a steel mill. For "water", it might be an ocean park or a cruise liner. For "air", it could be an airport, or the top of a skyscraper.
Then I think of the basic Feng Shui 2 adventure structure--Opener, Bridge, Climax. I'll pick one setting for the Opener, put a couple of ideas for the Climax in my pocket for later, and start playing.
I generally don't worry about how the heroes met, I just say "You've each been following your own quest and you've met up with each other. Now you've punched some people in the streets, and you've gotten a lead to the ninja clan who killed the Martial Artist's master and who kidnapped the Private Investigator's daughter."
Then they have the fight at the Opener, maybe it's a mountaintop temple in the Past Juncture where the ninjas are hiding. Fight some ninjas and discover that they killed the Martial Artist's master because they're on a quest to be the ultimate martial power in the world.
Once they defeat the ninjas, they find that they kidnapped the Private Investigator's daughter because she was prophesied to be the reincarnation of an ancient magical goddess. The ninjas were hired by a Sorcerer from the Ancient Juncture, and they've got his location."
So then they go to the Ancient Juncture and fight the Sorcerer and his demons and snake people. If you've got time they can find a clue that the Sorcerer has been working with a Mad Scientist from the Future Juncture, kidnapping people to try to combine demon and magic.
...anyway, that's just an example 
In completely improvised games like this, I tend not to worry about the details of the various factions and I often omit the existence of the Netherworld entirely. I'll just have a portal go straight from a hotel room at a Macau casino in the Contemporary Juncture to the top of a mountain in 1850s Tibet.
Don't worry if you can't get to everybody's melodramatic hook, I'm sure they'd have a good time!
Those are brilliant. Thanks a lot! Exactly what I was looking for both for in game and to alert me to key things as I prepare.
Those playmats are an excellent idea - how big are they? Another GM got some map printed on some form of special material for one of his games, I may get one of them printed.
Thanks!
The playmats are 24x36", I believe. I took them to a copy shop and got them printed out in color and laminated. (It cost around $100 to get it done for all 5 Junctures, but it'd be more affordable to get only one done.)
Just in case you've got the cardboard Shot Counter from the Kickstarter, it fits perfectly onto the image on the playmat--or you can obviously just use the playmat's counter.
Not only is a physical version of said sheets awesome on a gaming table, they also scale pretty well in roll20 with tokens movable by player and GM alike (depending how much you trust your players). 