If you meet a parent at the park that seems nice and/or the kids get along well, how long until you ask for their contact info?

We just met a super cool mom and her kids at the park and I wanted to ask for her number or something, but my shy nature took over and I didn't do it. Meeting anyone at the park is rare around here, let alone someone we'd want to hang out with! This whole situation makes me feel like I'm on the dating scene - haha.