I'd wait for us to finish the 2k9 file before you start. Ratings wise it's going to be pretty much spot on, so hopefully that would reduce the amount of time to rate them for next year quite a bit. We'll also have the coaches, recruiting strategies, etc done so it'd be better to wait for it so that doesn't have to be done again.
It'd probably be better to wait until the end of the season anyways so all of the recruits will have commited.