Part-time jobs that fit around childcare

I am looking for part-time work that fits around school hours and found a few evening shifts near Buffalo. I do not usually post, so bear with me. Shifts are four to six hours and the pay is weekly. Is the schedule really fixed?

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.

Ask whether the schedule is posted in advance and how they handle swaps. It matters a lot with kids.