Both my boys, with late September b-days, started preschool right before they turned 3. It seems like a fine time to start, as long as your child is exposed to puzzles, games and books now. If your son has scheduled meals, snacks and nap/sleep time, he is having enough structure in his life. Preschool is alot more demanding, and any added maturity on his part is always better. Besides, at this age, socialization is what's important, and it sounds like he is getting that.
Good luck!

My son is only 15 months old, so I'm not thinking about preschool just yet, but it seems to me that there is some value in learning to relate to children who AREN'T his age. He'll be with kids his own age for the next 14 - 18 years.

Plus, if his caregivers are "like family", I think you should take advantage of the positive, nurturing environment for as long as possible!

I would agree with MM2. Two was too early for my October bday oldest son. He was adrift and a follower in his two morning a week program which began just as he turned two. At the age of 3 1/2 we moved him to a five day a week preschool that had an afternoon extended day option, and he took off. Our youngest, with a May birthday, started preschool in September at almost 3 1/2, in a 5 morning a week program. He was more than ready and had a great time. When our kids were not in school, they were home wiht me or our nanny.

both of my kids entered a preschool daycare at 2. The 2 year old class was a lot more playing than structured learning but as they progressed from the 2's to the 3's and 4's things evolved. At two, having a schedule was enough and got them on track. At 3 and 4, having circle time, learning letters and words associated with the letter, learning about holiday's like MLK day or Presidents Day, having books and crafts, computer learning, etc etc. has really prepared them for going off to kindergarten.

My son was diagnosed with ADHD at the end of his kindergarten year. had he not had preschool lay the foundation for expectations, he probably would not have made it at all. He knew what was expected of him but couldn't get himself there. During our discovery phase it was hard. But now, he is a happy learner and I credit his preschool teachers with getting him started.

My daughter is 4 now and will be going to K next year. She loves preschool and can't wait to get there everyday to learn. She too will be ready when she gets to K and won't need to go through the Mommy withdrawl period....we've already done that. She knows what to expect and what is expected of her each day at school. She understands her routine and can't wait!