Dude, the longer you wait the better, when you fill up a tank, you put stress on the joints and silicon. No one can tell you the exact second that it is ok because it depends on 50 things. However, the longer you wait the better(no rule of thumb there its fact), 48 better than 24, 72 better than 48, ect.
Compounds may "cure" but they get stronger over time. Concrete continues to harden(cure) for over 50 years, but you can start building on a foundation after 24 hours if you wanted to, but if you were living in the house and 48 hours is safer for your family what whould you do? No, waiting 24 hours isn't necessary, but since no one can be sure of the exact scenario you are facing, I would wait at least 48 hrs. This tank is going to be part of your life for years (hopefully, or you may get the gallonitis like I did upgrade quickly), so what is the harm in waiting another day to be sure you did it right?
No one is going to take the time to teach you the chemistry of compounds curing here, but I can assure you(from my own experiences) that the end result of rushing things in aqurium keeping will most likely be dead fish and dissapointment.
Make your own decision on what you think is necessary

Keep us posted and good luck!