My daughter goes to Wee Care International Preschool on Rt. 23. Their hours are 6 am to 6pm. I know this doesn't meet your 8 pm request but I just wanted to let you know about them. Maybe you could have someone get your child at 6 for the last two hours. They (Wee Care) are AWESOME!!! My daughter is 18 months old and LOVES going everyday. Anyway, when I was searching for daycare in Okinawa this was the place that had the longest hours and also the place that was the most flexible. I hope this has been some help to you. Good Luck!
T.
PS - What part of MD are you from? I am from Waldorf, MD.