Trust the vet for now, it’s very age and weight variable.

On which note: call your chosen vet and pre register your cat. It’s easier to get an appointment if you’re already in the system

I haven’t had to look after a cat in a long while. Someone else would be able to advise you.

My most recent pet was a dog and I got some flea and worming cheese things from the Vet when I did a checkup there.

Mind you this was some years ago so I wouldn’t have a clue at the moment.