I have to do 3 cakes for next weekend. One is a 3 tier wedding cake. I baked last weekend and froze them. My question is how far in advance can I thaw, ice and start assembling? I'm a newbie btw

For a Saturday wedding, here's my schedule:
Thursday, pull layers from freezer, fill, wrap, weight and let settle.
Friday ice and decorate, sometimes stack.
Saturday, deliver.

Yeah, I mostly agree w/Leah. Lots of times I'll transfer layers from fzr to frig overnight on Wed. It does depend a bit on how big the layers are. A 16"er takes longer to defrost completely than say an 8"er.