Occasional Sitter, Flexible Hours

So I have two girls right now (2. 5 and 15 months) and am due next month. I stay home and am not looking for something with a set schedule, but I know with 3 under 3 I could use some extra help when my mom isn't available. I've never had a babysitter besides family before but my parents aren't always available so we're opening up the idea of an occasional sitter. We would want to start with a date night here and there to get the girls adjusted, then whenever I have the baby next month add something more, possibly 1-2x a week as needed if things go well. Sometimes it would be just watching the newborn while I take the older girls to do something fun, or maybe watching the other 2 if I have to take the baby somewhere, & sometimes all 3 if I need to do something on my own, or have someone around to help me out with all 3 at home.