Don't forget you must get transcripts, LOR's, etc in, application verified, and so forth before your app can even be sent to schools. This process can take 1-maybe 2 months to complete, as some schools are slow sending transcripts (especially around holidays) and AACOMAS may take a month to verify (often less but they do get busy) and med schools then have to sort through apps to decide who they interview. Then if there are errors in your transcript that can take time and secondaries can be time consuming.
The issue with waiting until Dec/Jan to submit to DO schools is that you are also now competing with a TON of other MD applicants which have great stats but that got no love from MD programs.
Some DO programs also want a DO letter and some are very strict about such!
So don't expect to start Dec 15th and be done by Jan 1st. IMO, I'd work on getting things into AACOMAS and verified so if I got no love I could pull the trigger mid Nov and submit broadly to DO schools. The cost is minimal up to the point of broad submission.
Good luck