Sulphur vents quickly as the primary commences, and I've definite recollection that lower temperatures will induce sulphur production at a higher rate during fermentation, but google and my memory fail me as to where I read that.
When making wine, you often rack the wine to aid in getting rid of sulphur - in beer, I suspect you'll get the same effect when kegging.
Also in wine, leaving it in the primary is a nono when sulphur dioxide is around, because it can bond with other chemicals to form something that remains in the finished product. If it were me, based on this trio of anecdotes, I'd rack about a week after primary stops (no sooner to allow for the majority of conditioning, no later to avoid potential permanent skank).
