N.C.
So much of preschool is social development and handling oneself in that environment in preparation for Kindergarten - detaching from parents, listening to unrelated adults for several hours at a time, sitting in circle time, lining up, taking turns, eating with others, sitting at a table for short periods of time, ignoring distractions from other kids, etc. If you plan to place her in public or private kindergarten, then I strongly suggest placing her in at least a 4 year old/preK preschool program so she has these social skills strongly under her belt by kindergarten - especially if she is smart & strong-willed. Kids tend to have issues in kindergarten much more because of their 'rule following' than for lack of intelligence.
Best wishes,
N.
mommy to ds8, dd5, dd3