oh yeah,... take them at the next chance you get.
The shots are a series spread over two visits, as are the de-worming and such.
You deal with fleas by spreading their fur between their shoulders to the bare skin and put some gel you get from the vet on it. You apply it between their shoulders so they can't lick it...also keep them separated for an hour or two.
At 6 months for little boys....you get them neutered. Some people will flinch at this, but with dogs, cats, and horses, you don't want to deal with unneutered males.
For little girls 4 months for spaying. And little 4 month old kittens can indeed get pregnant.
After the two initial visits and fixing, you want to take them in every 6 months to a year, and you will have to get a prescription written for the flea gel. The flea gel is important, it is the only good way to deal with fleas. They will also check for parasites. They...run a skinny plastic probe up their butts.
The best way to keep cats, if you can do it, is to have a pair. By far, a pair of cats are much less trouble than a bored single cat. They roughhouse together which prevents them from clawing inanimate objects. They also develop a sense of how hard to play when they play with people from their play fighting together.