Re: How do you do playdates?
I would schedule a day and time a week (or however often) for the playdate. That way you can incorporate that into your schedule. If you don't want to make lunch I would do it after lunch or ask for everyone to bring something.
My play group is every Friday in the afternoon. We do have lunch but everyone chips in. In the summers we just do it at the park so no one has to clean up.