i'm preparing to ganache a cake (for under fondant) for the first time and would like to do things as late as possible in the week to ensure the cake is fresh for the sunday christening. Is it possible to make ganache in the morning and have it firm enough to ganache the cake by the afternoon/evening? I'm then planning to fondant the following morning - does that sound ok?
AYep. Try to let it rest for a couple of hours. Should be fine :).
AI make ganache just before I get the kids up in the morning - about 6:50-7ish, I pour it onto metal trays to cool faster, I take the kids to school, I'm back at 9 and the ganache is ready to work with. Of course it depends on the weather, but give yourself a few hours leeway and you'll be fine.
It depends on the weather as well - it can set in a couple of hours, but I just wouldn't risk it.
Ganache is fine for weeks at room temperature. You can taste absolutely no difference between ganache made 6 hours ago, and ganache made 24 or 36 hours ago.
IMO, it's far more important for it to be set sufficiently to work with, than to be 10 hours' fresher.