I can see why you love him already!
As a new cat owner there are a lot of pitfalls (I've stumbled into plenty in my time). Figure out how he acts normally, and whenever he strays from that normal - go to the vet.
For example: regular advice is if cat seems more withdrawn than normal they are sick - for me cat was more affectionate than normal so didn't realise they were sick,
Another time I was toilet training cats, and the one who got it turned out to be sick, because potty training isn't very normal and hides changes in urine and poop schedules.
And speaking of: if you have outdoor cats, keep them inside for three days now and then to have them go in a litter box just to check that they don't have parasites, bloody stool, pain around peeing, frequent pees etc.
If its an option, always have the insured for the vet, and better safe than sorry. Cats are experts at hiding their pain and injuries until its too late, so any change can be a symptom.
Not to bee a gloomy doomy - my current bastard is nearing 20 years old (with regular vet visits and daily medication no one guesses his actual age). They are for sure the light of your life, and I hope you have a long full life together!
