No matter what, don't go in the winter.
As someone who hates the cold with a passion, there's nothing worse than waking up cold in the morning because you either didn't have on enough to keep you warm during a cold winter night in a sleeping bag or had on too much and wake up cold from sweating throughout the night.
Winter campouts are the only camps I absolutely do not miss at all from my time at scouts. The cold mornings are enough for me to not suggest it, despite it not actually being that bad after you've warmed up.
Though, on a more serious note, one of the things I do remember being taught but never followed through with for various reasons is to put your clothes for the next day under your sleeping bag so that way the next day they should be warm or at least warmer so you aren't putting on freezing cold clothes. Especially good for things like jeans because there's nothing worse than putting on jeans with frigid cold metal buttons if your hands are already trembling a little from the cold winter morning in general.
Normally I'd be on solid ground, in a tent, with a sleeping mat beneath my sleeping bag, so it would probably be safe to keep my clothes under it, probably towards the end of the bag near my feet. I've also never had any sort of ice forming on my sleeping bag before since we always had tents for every campout as needed.
Maybe I'm misremembering the advice or it's bad advice, but in general I am probably never gonna have another chance to test this advice. So I'll take your word for it.