Right now, I'm working on a peach wheat beer. I pitched about 5 days ago now, and the airlock stopped bubbling yesterday. I'm going to do a gravity reading later on today to see if it's finished. My current plan is to rack the beer onto the peaches in secondary, which I've seen recommended in several places. My question is, how long should I wait between primary fermentation finishing and racking onto the fruit? I know right now the yeast should be cleaning up after its self in the primary, and if I wasn't going to be adding more sugar (in the form of fruit) in, I'd definitely leave it alone for a while. But, since its about to go ferment again, should I give it time, or can it do clean up once it's done fermenting the peaches?
It sounds like you already know the answer. You want to wait until the gravity has evened out and off flavors are cleaned up, but not so long that the yeast have all settled. You also want to be sure enough yeast are floating around that fermentation can quickly start again and any bacteria that rode the fruit train will be outnumbered. I usually give it two to three weeks. Follow the advice offered in response to this question and you can't go wrong.
I just finished my PeachFuzz Wheat Beer... basically did what you were talking about and it turned out very good. The only problem I had with this mix was with carbonation. After I moved it to a warmer place (about 75deg) it carbed up and is very tastey. I love it! Good luck and I hope it works out for you!