As an infant teacher in Scotland, I would think about:
How will your child cope emotionally with the reduced adult/child ratio? 1:8 in nursery and 1:25 in P1 in my school,
How will your child cope socially in the playground with the reduced adult/child ratio. 1:120 ish in the infant end of my school.
How will your child cope in the dinner hall with the reduced adult/child ratio? 1:100 in my school.
Is your child ready for learning - sitting, listening, following instructions, etc?
How is their fine and gross motor skill development? Can they draw a recognisable person? Can they do up zips, buttons, Velcro, open packets, etc?
Do they know 5 nursery rhymes by heart? Rhyming is the step before phonics.
Can they play a board game and take turns?
The hardest of all: can you predict how they will cope with P7/S1 transition? S6/Uni transition.