I used to take my son to a daycare a couple of hours a week for socialization. I found a daycare that also did pre-school and followed a curriculum for each class. My son wasn't fully potty trained at the time, but i found that because he didn't socialize with other children his age this was a good experience to help prepare him for school, he made friends and learned things.
Most pre-schools and kindergartens will give you a list of the things your child learns through their curriculum, but they also ask that your child be able to do a few things prior to school.
Curriculum Standards for Preschool | Typical Course Study for Preschool | Learning Standards for Preschool This list is for a standard pre-school. I suggest you contact the local school you want your child to eventually attend and ask them about their requirements for attending school. It sometimes differs from school to school. having said that, I still highly suggest socializing your child, through friends or a couple of hours in a playcare a week or even monthly. It can help you both adjust when school finally does come. Good Luck!