vet checks

as soon as you get your new kitten or cat, you should register it with the local vet.
the vet will then perform a routine examination (checking the heart, breathing, ears mouth, eyes, coat, weight and abdomen and the general appearance of your cat) he will pick up anything which might be wrong with your cat at an early stage. especially when you don't know the history of the cat (in case you have picked it up from a shelter or was a stray)

after the inital check up you need to see your vet every 12 month for further routine check ups. when the cat is very young you are advised to see the vet when its 8, 9 and 12 weeks of age (vaccination course)
when your cat reaches the age of 10, it is sensible to visit the vet every 6 month for a general examination.

in the meantime you can do your check up routines once a week. the best time might be, when you groom your cat or after feeding it or when it hops on to your lap for some cuddles. just take a little time and check on its ears, eyes, mouth, coat and rear to make sure all looks clean, and healthy.