Actually, you should avoid using vacuum full at all. What that operation does is creating a new table with contents of an old table then deleting the old one. This operation is also requesting an exclusive lock, so any write query will cause lockup.

Another problem is that vacuum full compacts the database, it reduces database size on disk, but doesn't mean it makes database faster, often it might actually reduce performance.

Vacuum full might be useful in scenarios where you want to reclaim space, because autovacuum was not tuned correctly and tables get out of hand, if you need to run vacuum full frequently you should tune autovacuum to run more frequently.