4 year old not made friends at school

My 4 year old started school in September and doesn’t seem to have made any friends. We’re in half term at the minute and he’s desperate for other children’s company but I don’t know what to do to enable that.

I’ve tried reaching out to his old nursery friends parents but none seem to want to arrange anything so I’m stuck.

I know it’s only October but he’s not had any invites to birthday parties from school and I’m starting to worry that he won’t.

Is this normal at this stage of school or should I be doing anything to encourage it?