Typically I consider my sermon is done, i.e. ready to preach... (remember these polls are totally anonymous)
More than a week before I preach it
On Monday-Wednesday before the Sunday I preach it
On Thursday before I preach it
On Friday before I preach it
On Saturday before I preach it
LATE Saturday night before I preach it
Early Sunday morning before I preach it
I'm still working on it during the worship time before I preach it