"...The start date for e-filing isn't that important, is it?"

Not for me, or for my clients.

1) I don't start appointments until late January (not that I'm doing in-office ones this year)

2) Few of my clients are overpaid, and if they are - it is usually applied to the next year anyway.

It's the self-prepared folks that are in such a hurry as they can't/don't manage their withholding to avoid lending all that money to the government for free.  Or the ones getting those large subsidy payments of CTC, EIC etc.

And do any of those folks even HAVE their W-2's yet ?!?!  Perhaps I'm just living in a different (tax) world 😂