When mine was replaced a few years ago, when I came home from work, the pool was filling and the vac was running.
The guy left a note saying not to turn off the vac until the water was up to the piece of tape he put in the shallow end wall.
(amounted to about 1 foot of water in shallow end).
I was a bit nervous about it, worried it would take longer late at night (vac was industrial grade and LOUD).
I have neighbors close by and didn't want to annoy them. Lucky for me it was at the tape line around 10pm.