Welcome!! No that isn't too early. You can make it for a cake this weekend. Actually, it is easier to work with if it "rests" at least overnight. I make a batch and keep it sealed in a zip-loc bag and then when I need it I have it ready to go, I just need to color it. I mostly use it for decorations to put on my buttercream iced cake since that is what everyone around here prefers!!
Again, Welcome to CC!!