I would go for it so as not to spoil the moment or make it awkward, but let him know afterwards sometime maybe.
19 is totally still acceptable to be learning how to kiss in my opinion... besides kissing is different for everyone, so no matter what there is lots of improvisation and learning for the ques from someone.
Here's the thing. Unless you try to swallow him, or lick his tongue like a cow, or make grunting noises like a pig, YOU WILL NOT BE A BAD KISSER IF HE LIKES YOU.
Yep. If he likes you, he WANTS to kiss you. WANTING to kiss someone is about 90% what makes it wonderful. The first time I kissed a girl, I didn't really have my heart into it. It wasn't great. The first time I kissed a girl I liked, I swear I went over the moon. I didn't do anything different. She didn't do anything different from the first girl I kissed but didn't feel anything for. The ONLY difference was I liked the second girl and didn't really feel anything for the first.
Maybe you can tell him afterwards if you like. It might make it all the more endearing.
I told the guy before I kissed him and everything went fine, but I think it all depends on the guy. I would just let it happen and tell him after or later. Don't think abut it too much because then it might be awkward or something. If you just let it happen, it'll come naturally. Good luck!
I think it depends on the guy, and how superficial or genuine he is. I had never kissed anyone before my first boyfriend, when I was 18. I didn't tell him, but when he leaned in to kiss me I panicked and leaned away lol He was sweet about it though and kind of walked me through it, and didn't pressure me. He just made me feel really okay about the whole situation.