As per Microsoft documentation Learn about automatic SQL Database backups
How often do backups happen?
Full database backups happen weekly, differential database backups generally happen every few hours, and transaction log backups generally happen every 5 - 10 minutes. The first full backup is scheduled immediately after a database is created. It usually completes within 30 minutes, but it can take longer when the database is of a significant size. For example, the initial backup can take longer on a restored database or a database copy. After the first full backup, all further backups are scheduled automatically and managed silently in the background. The exact timing of all database backups is determined by the SQL Database service as it balances the overall system workload.
Is there a way for me to check if my first full backup is completed and ready for restore?
I understand it will be first available in the same location and later replicated to other locations. I also know that I can check by trying to add a new database from backup and see if my database backup shows up in the list. I am more interested if there are system tables, management views that I can query to check?