I always though it had to do with what your rating in other time controls were, but i am not sure.
Starting rating

Alwyn!!!! Funny you should answer this question...I'm asking for an idea I'm brewing which may or may not involve you, if you are interested. But I need to do some more research before floating the idea (elsewhere)

Good question. My son plays some blitz, but I am recently playing him at his first daily game. Some sections of the site day his daily rating is 1200,others say its 400!

I can't see anything obvious on this from a search.
If someone has never played a Daily game, but has played plenty of live chess what does their rating start as for Daily when they first join a tournament or match? I assume it depends on the level they chose when they first opened the account rather than anything based on their live chess ratings?
It starts at the same point the account started at.

I have never played a bullet game, and my bullet rating shows as 400. Back when I joined chess.com, everyone got 1200 as starting rating, there was no option to choose your starting level.

Yeah, same here about all being 1200 when I started, except I've played in all time controls so all my ratings have an actual value by now.
Yeah it's entirely dependent on what level you chose when you started the account. That's why my rating starts at 400.
I can't see anything obvious on this from a search.
If someone has never played a Daily game, but has played plenty of live chess what does their rating start as for Daily when they first join a tournament or match? I assume it depends on the level they chose when they first opened the account rather than anything based on their live chess ratings?