condoms

might be a stupid question but i’m asking bc i don’t know alot of STDs/STIs. i just started having sex and my partner has only slept with 6 people (i’m his 6th). last time he had sex was about 2 months ago (with someone other than me)... should i still tell him to use a condom? or is the chance of a STD/STI very slim? how long does it take for something to appear? should i be concerned i have a chance of getting something from him?