I've added a prayer schedule, courtesy of Islamic Finder. It's set up to give the times according to the Maliki Madhab. The time for 'Isha is about 50 minutes after sunset. According to the Guiding Helper, you can use a 120 Minute rule for calculating
Subh (Fajr), use a local prayer calendar, or check the sky. It states that one shouldn't argue whether 120 minutes is exactly 21 degrees, but since I have the option of setting according to either measure, this doesn't help. I'll have to do more research in order to determine what the permanent setting should be; in the mean time I'll use the 120 minute rule. If you have doubts that Subh has started, check the sky outside.