Dont take this the wrong way but its best to save the second dress until later on. ON a first date, you dont want to reveal a lot and , at the same time, you dont want to be too conservative. im not sure where yiu going so... Since you're a teen, here are some ideas
well i would definitely go for the first one no question! cute, classy and sexy! the second dress is super fabulous, i totally love it but i would either keep it for another date :) for the first date you dont wanna reveal too much, show him that you're worth more than that and i bet you are! for first dates with guys i usually go for something eye catching but also not too revealing which is what you have going on in the first one!
also, a good idea would be a pencil skirt with a cute top :) dont forget to match the shoes and bag though!!
I like the first one. It looks really CUTE and really nice for an evening out! There is nothing wrong with CUTE!! The second one looks like it's about to fall off so you could just save that for the bedroom.