You should always vaccinate your Cat regularly in order to retain a healthy Cat.
At least the following should be done on a regular basis :
Cat Flu/Rhino-Tracheitis

In addition to this - if your Cat goes outdoors :
Rabies
Leukaemia (FeLV)

Please ask your Vet to check the Cat PRIOR to vaccinating, if he/she may possibly have any other Infection.
Rabies- and Leukaemia-Vaccine does sometimes cause unpleasant side-effects and should be applied to healthy kittens/cats only. They should be given separately, not all at once and should be applied only to Animals which have been thoroughly wormed and completely free of any Parasites prior to vaccinating.

1.First Vaccination should be given at about 8 - 9 weeks of age (with Pedigree Cats the
Breeder should be responsible for this)

The second Vaccination should than be repeated 3-4 weeks after that, not later !
Incase of a Pedigree Cat, the Breeder is also here responsible for this.

2. Rabies: at the earliest at 13 weeks of age if the Cat goes outdoors or goes to Shows

3.Leukaemia: never under the age of 16 weeks, as some Vaccines can be a big strain on
a young kitten.

Again, this should also be repeated within 3-4 weeks, not later!

It is of utmost importance, that these Vaccinations should be repeated at least once a year, in some cases every 2 years, depending on the Vaccine.