Congratulations, man! I'm transitioning to this sort of thing myself (going from 6 figures to a pt gig, 2 days a week). My suggestion: get a whiteboard, now. Don't do anything but decompress for the next few days (i.e.. fuck off) and write anything that comes to mind about your startup. One of the most important processes for the human brain is externalization: it's why talking about problems helps as you can't think…
Decided to enjoy the great weather here, drive around a lot and play with legos :) The real work starts tomorrow