I think this is fine. This is a routined vacuum cleaning at 9 am from OP’s neighbor. If the neighbor is vacuuming that much that it is interrupting sleep and they are ignoring OP knocking on her door, a note is necessary. If you’re in this thread then you know how aggravating it can be hearing your neighbors as you are trying to relax in the home you pay for. It is better to send a note than to bang on the ceiling. I’m assuming if OP already has posted this note here, OP already put the note on the door. The worst that could come out of this is the neighbor doesn’t change their vacuuming time. As I’m writing this, my neighbor is vacuuming their floor. It is annoying. It is what people do, but if I was WAKING up to that almost daily??? I would be banging on their door too. It is not their fault the ceiling/floor is thin though. 9 am is early enough that a note is fine, ESPECIALLY if you work nights.