I think manga updates are based on the UK time. Whenever I post a comment, the time is always 5 hours ahead of the time that I actually posted it. And usually you get the notification of when all of your mangas are updated at the same time regardless of when they are updated. Some times you just get a late notification. For me, it usually updates between 7:30 am and 8:30 am but there are times I don't get the notification for it until almost noon
The notifications come in once a day. So if the chapter is uploaded 1 minute after notification time you have to wait 23:59 before you get the notif. Yes it sucks.
In my timezone I currently get the notifs at around 1 pm.
For some reasons i'm not getting notifications about updates even tho i put them in "already read list" What could be the prob? T^T