After I silicone my fish tank, how long must I leave the water in before I can put my new water in and fish?

I just built a new fish tank. Now I have silicon-ed the whole thing and I put water in to make sure it does not leak. Now I know I must leave that water in there for a while so that it takes all the chemical out of the silicone before I can put my fish back in with fresh water. But my question is how long must that water stay in there before I can put new water in with my fish.