The start time should be based on water usage in the home, evaporation, and disease.
It is best to water when no other activities are occuring ie showering, laundry ect...
Also we want to water during the cool part of the day to avoid evaporation.
Although it is cool at 10pm this is a bad time to water because the wet grass night after night will lead to disease and fungus problems.
I think starting at 5am will be fine provided no showering activities will ocurr prior to 7am.
FYI I start my watering at 3am so it finishes at 630 and I have not had any fungal or other problems.
Also it is best to water less frequent and for a longer time. You may want to think about watering each zone for 2 hrs every third day therefore do zone 1 for 2hrs monday zone 2 2hrs tues, zone 3 2hrs wed and the start over on thurs. Your timer may not be this flexible but it is just a suggestion.
Thanks,
Pete