curing time

If my tank was newly built, like within the last 2 weeks, should I wait a while to fill the tank with water? Somebody at my LFS said he would wait another week or two. He said even though they say the silicone takes 2-3 days to set, he's seen new silicone split when a tank is filled if it...

I made some caves with plastic cup/glasses that I heated formed and covered with silicone and then rolled in sand. I love the outcome but I have no idea how long I should wait before adding them to my Dwaf crawfish tank. I've already waited 24 hours