Nervous

so i met this guy through a club and we started talking and i had a huge crush on him thinking he didn't like me back i ignored the crush and it went away after a while but i still talked to him 24/7 everyday since then i just convinced myself we were just friends. Fast forward to two weeks ago he asked me out i said i couldn't since i'm only fiftteen and my parents rule is sixteen i said it's only two months but i'd rather wait he said that he would ask me again in two months then asked me my birthday. The next week he asked me to prom i didn't give him a direct reponse but later on told him i would go. This is my first relation ship and i'm super nervous he's a senior and i'm a sophomore i'm so nervous but he's a great guy all of my friends say i should go for it because he likes me for me and he's not trying to use me for my body like other guys do. How do i calm these nerves and how was ur first relationship