Anyone work in Early Learning Scotland?

Wee man got his letter about His early learning / Nursery thing today.

I've not long moved up from England so assumed would be same 4 years old you're in nursery and would turn 5 at some point during primary 1.

Wee man is only 2, turns 3 in July so would only just be 3 as starts Nursery and letter says 9:00am - 3:00pm that seems alot for such a wee guy says "Core placement details" Mon-Friday 9-3 so is this optional got some wiggle room?