After re-sealing mine I let it sit for 72hrs before adding water, primarily because I was too busy after 48 hrs to get started, but I also waited until the smell of the silicone went away. I figured that was a good way to tell it had cured.
Since my situation is a little different, I have to do my leak test inside the house rather than outside. So I'm doing mine slow. I filled a quarter of the way up the first go round, then the next night went to half, then to 3/4, then full. That way if it did leak while I was away, it wouldn't be as big a mess. (I know that logic doesn't make sense but hey, it did to me after a few beers...)