We usually eat dinner between 7 and 8 at home, so that is when I made our ADR's for. It is a very personal decision. Dinner at 5 would be way too early for our family. Also what time do you normally eat lunch? CS lunch with desert was a lot of food too, so we wanted to leave time between finishing lunch and having dinner.
The later into the evening your ADR, the more likely that you may have to wait a bit.
Make your ADR's at whatever time appeals to you and your family and enjoy!