My son who is 3, is going to forest school nursery & he’s never been away from us before! :(

Just because he’s booked in for 5 sessions doesn’t mean he has to attend 5 sessions. I’d just send him for the 3 mornings you work ☺️

You can always start and take him out if he’s not enjoying it. 9-12 is not long days, he might just be worried to begin with but actually like it once he’s there.
My eldest is in the same school year and he starts school nursery in a couple weeks and he’s very excited cause he’s been there to view and he loved it, makes me feel better about it because he’s also never been in childcare before.

we’re getting ready for my 3.5yo’s first day of prek 8am-12pm. does the school allow parents helpers to stay for the day? Im assuming your son avidly loves being outside

He'll be fine once he starts. They'll be plenty of other kids who don't know anyone. Keeping him home and away from "fear" won't do him any good as he'll feel this way about starting school and that will be much harder.
You could always look at another pre school and just put him in 3 days. Most kids do 5 half days x

My 16yo is telling me that about college! Ha!
It's normal for your son to be a bit nervous before starting, but forest school is amazing (I'm a FS leader myself) and I'm sure he will love it once he gets to know everyone! x

I would still send him all 5 days to keep his routine, he only goes 3-4 hours so you will still get time with him in the afternoons and everything so it will be good for him to go and learn , make friends and learn to be away from you a little bit ! 💖 I think it’s harder on me to send my son to prek for 4 hours then it is him lol