I would just chat with a DMV agent via their website (click "Ask DMV" and then type Agent). Ask if they have started processing the registration, they will need VIN and registration details (the first few times, they told me they received nothing, and the last time they confirmed they had received something, but couldn't confirm details).
This told me they started to process the registration and I dropped my application in the mail the same day. If they haven't started processing it yet then they will just reject your application. I submitted it with just the VIN filled in as others have done in the past.
Make sure you have the latest 12/2021 form.