This has probably been asked a zillion times.....but if making poured fondant do I have to use immediately?? Can or do I let it stand.....if so how long can I leave it before using???

Sorry! I don't know the answer. But here's a BUMP for you!

It will start to crust pretty quickly. I have to tell you the one time I tried to use it was a complete DISASTER. I tried to coat 2" cake pieces. I threw the third and last one I had in the garbage after crushing it in frustration in my fist.

Good luck if you try it. Hopefully you will do much better than I did!