I have made calls on Sunday for years and it has never been an issue. I start around 4:30pm. I use to do this exclusively for years. Now I call Saturday mornings, but will call Sunday if I need to fill some slots in my day, or if I'm busy on Saturday.
Behind Saturday morning, Sunday (early evening) is the best time to call to set appointments. People are home!!! People are less likly to screen their calls on a Sunday too. That is the biggest obstacle of dialing during the week, in addition to trying to catch them at home.
Travis you are only confirming what my instinct tells. People are pretty relaxed late Sunday afternoon to evening and I would think it an excellent time to call DMV leads.