For Belgian Wits, I would go higher than a German Hefe. The wit strains are thermo-tolerant, and the esters and phenolics that result are generally considered part of the profile.
I've done the 66-68F and raise method as described by Pie Man, and this works well. I've also done 68F and leave it there for the duration of primary, and this also works well. I've also heard that mid to high seventies to low eighties works if you want to get a little more of the juicy fruit/bubblegum notes, which I'm told can be a nice balance if you're using any form of sour mash in your wit (which I don't).