The diagnostician we used says there are tests normed down to age 2--my kids were tested at 4-5, and that was considered young. She says she would cancel if kid has an off day, but since she doesn't know my kids--how would she know when it's an off day. I would keep goals in mind when you test...since you want to get into the preschool, test as close to deadline as you can. My kids who skipped early had a little trouble with dexterity skills (writing). IQ scores for many things are valid for 2 yrs, so you want to make sure it's valuable.
