Hey good for you and your friend. I would try The mall. Most have a play area. Instead of pinning them up just walk up to Mom's and say. "Hi, we wanted to introduce ourselves I'm ______ and this is _____ if you ever need a night out or a break from the kids, here is one of our fliers."
If you want to post the fliers go to laundry mats, apartment complex (Ask Manager 1st) Parks have bulletin boards, The grocery store, hair salon, nail salon, cub scout meetings, girl scout meetings, church.
Hope that helps. Good luck.