how do you know when you’re really ready to have sex?

do you just feel like youre ready? i’m with someone i love, i’m 19, and this saturday i might have sex with him. he is not pressuring me, i’m more pressuring myself. i feel more ready than usual just because i’m finally with someone who i know will last. i just am so scared that it will hurt, and i’ve been taught to not have sex my entire life. what are the hints that you are ready? how will i know?