Automatic Reminder for logging times

We use timesheets & set up reminder notifications 1) reminding staff to close their timesheet on the last day of the timesheet period and 2) reminding staff that forgot to close their timesheet that it is still open. We accomplish this via Set Up > Email Notifications > Reminder Notifications. Though I will warn you that that we keep having problems with the delivery date of the emails/timing. #1 should come out on Friday & #2 should come out on Monday. They worked properly & then did not. We worked with Workfront to get them set up again and they worked for a while. But now, they are coming out 1 day too soon. (Thursday & Sunday)