Submit it ASAP or NOW!
I have personally had former students say that they were unable to submit their applications because the UC system crashed. It always seems to crash.
We always advised students to submit by Nov. 15th. If a student submitted by Nov. 15th, and there was an issue, those students were prioritized for help because they followed the instructions and had their act together. (The counselors had virtual and RL posters, fliers, announcements, contests for swag, with Nov. 15th submission ads.)
The students from California tend to have this week off, and some have procrastinated until now. The UC’s try to have technical advances in place because they are always overwhelmed on Nov. 30th, with hundreds of thousands of applicants from every city, state and country.
Also, if there are issues on the app, the university IT people can answer and debug some issues, but NOT NEXT WEEK because they will be overwhelmed and will not be sympathetic if you’ve waited until the last minute.
You will be waiting a long time for help from your school counselors. They wont be in a hurry to meet with you nor your parents because they will be overwhelmed by appointments that have filled up their schedules.
We used to have lines outside the doors of the counseling offices during the last week of November. All 8 counselors and their assistants were swamped.
You can’t get in if you don’t apply with time. In the case of California publics, if you wait, you may lose your application in the “crash”.