Lulu I found that tricky in the beginning as well sitting there thinking should I pump... Nah he ilwill wake up soon and then sleep for another 2hrs! Grrr lol so frustrating. I use to find the more "routine" time was in the morning and I use to pump on the second side after his morning feed. So the 7ish o'clock on. Cuz then we were up for the day and I usually had some supply left over (boob still felt quite firm). I only pumped once a day at this time at the start to get a freezer stash and then if I then was out and missed a feed cuz he had a bottle I would then express when I got home and essentially restacking freezer. I was really worried about taking to much milk out so always did it bout 30mins after a feed and only ever one side. The second side and then would offer the first side first again the next feed... ITMS?
I know they say it's better to pump before if u can so bub gets hind milk but I just found it too stressful wondering if I took too much out!
I think boobs eventually thought I had a whole extra feed In the morning and could pump out 90-140mls on a given day. I've just started dropping the daily pump cuz we have too muh milk in the freezer and hubby and I are thinking about TTC again soon and hoping it might help AF make an appearance.... We shall see!

P.s I'm not sure if that helped at all! Lol