Difference Between Convergent and Divergent Evolution. When considering living organisms, evolution can be defined as the development of differentiated organisms from less differentiated pre-existing organisms over the course of time. There are many sources, which provide evidence to the theory of evolution.
You're apparently differentiating between daycare and preschool, right? Private preschools (about $500 per month for three days per week, 9:00a to 1:00p) typically have a minimum age of 30 months (2.5 years) and potty-trained.
Your child probably won't have a hard time in preschool if you wait till age 4, but you can also look at it this way: First, most kids start some preschool by age 3, and will spend 2 yrs with essentially the same group of peers, which is good bonding. Plus, it's enjoyable for her.