Preschool frequency for 3 year old?

[Jsgdud]

DS will start preschool when he is 3. He is currently nearly 2.5 and is quite shy in some situations and very wary of other adults/children when we are out and likes to know that I am nearby etc. Unknown adults usually comment, as if they try and talk to him he pretty much gives them evils or avoids eye contact. Grandparents currently look after him one day a week and that's fine.

Naturally, I'm a little worried about him settling in at preschool. What combination or days/frequency would help him settle? I was thinking three mornings a week to start? Not sure if consecutive or random would be better. Any advice?

My son started at 2,
We started with 2 half days, up'd to 3 half days. Now he's 3, he does these with one longer day.
Our aim is every so often adjusting hours for afew longer days to get ready for school.

He was only ever looked after by grandparents too, it took 2 weeks to have no tears going and I'd say a couple of month to be properly settled.

I would start with 2 and see how he goes, you'll know when he's ready to be up'd.