We tended to do them on Sat. a.m. or Sunday p.m. Although Sat. early evening works too if you are going to serve a meal.

It really doesn't matter. 4 year olds can go all day. I've even been to 4 year old parties that start at 7 at night.

We are doing 11-1 to try to accommodate napping younger siblings.

I agree with the PP that, at that age, 11-1 usually works best in terms of the kids' moods/behavior. Unless you know a lot of the kids' families go to church every week (which seems to be pretty rare in this area, other than maybe for Catholics, & Catholic churches generally have several mass times to choose from), Sunday morning might be better than Saturday morning for most people. There seem to be more kids' lessons/organized activities on Saturday mornings.

If your child is just tuning 4, some of her friends probably still need a nap (or at least some quiet time) in the afternoon.I'd try to avoid starting a party in the early afternoon at that age as many of the kids might get tired/cranky, particularly if they've already had a full morning. From my experiences (both as a host & a guest), until kindergarten parties usually go more smoothly if held from about 10-12 or 11-1 or, if that's not possible, later in the afternoon (starting around 3:30 or so) as to give the kids an opportunity for a nap or some rest/downtime after lunch.

Saturday afternoon, then Sunday morning.

We have activities Saturday and Sunday AM, so it would have to be PM.

Larla can be available any time from 8am to 9pm either day.

Would you pick Saturday am, Saturday pm, Sunday am, or Sunday pm? I'm thinking Saturday pm will be the easiest to organize.