K.O.
I think it is a good idea. My daughter benefitted from the interaction with other kids. we looked for a parochial school that had a 3 year old and a 4 year old program... She is now starting first grade and has been at the same school the whole time. The first week was a tough adjustment... but it has been good since then.
I would recommend it, especially with the new baby coming. I am just ending my 3 month materniity leave with my second child and belive me... it was such a help to send her to school during the day and give me some time alone with the new baby.
Most schools hold open houses a couple of times a year. They can be expensive though.
good luck