The answer is: It depends.
With regard to the length of the season, just look at HS football. There are programs already doing Winter/Spring football lifting. Of course, not officially, but the kids are nevertheless doing so with coaches "awareness".
Now when I was a young buck decades ago, I competed from mid-January until mid-July, and had I had the early December meets available then, I would've started in December and not thought twice about it. I completely ate it up and every meet was like Play Day to me.
With regard to structure of scheduling for coaches, early season meets are a great way to observe fitness levels of various athletes if not already known. It is also a great opportunity to get kids who have little-to-no experience in various events, particularly field events, to gain competency and confidence in competing in low-key opportunities that are few-and-far between these days with lack of dual/triangular meets of recent decades. Go for it.
Now with respect to experienced athletes that have already gone through grueling schedules during the summer/fall preceding, then I'd focus more on training than competing. Maybe a meet or two. However, you can't tell a kid he can't compete if he/she really loves it. No one could've ever told me no.
So, there's a quick look at the subject.
