I’ll be the first to mention sleep, but not what people usually say. As the father of two monstrous toddler boys with another crotch goblin on the way I should have a little cred in this dept.
STOP sleeping right now. Don’t try to save up any sleep credits, Mother Nature doesn’t give a fuck how many you have saved. She just chuckles and snatches all of them the first weekend you’re home. Get used to surviving on less than the absolute minimum. In fact, a good strategy would be to check what the Geneva convention determines as cruel and unusual punishment and, ehhhh, quarter it. That’ll be a good start.
Congratulations, welcome to fatherhood. It’s awesome but good luck