Most Helpful Guy
First off this is really sweet about you two going on your first date. Now I'd say it's just fine to say it's your first time kissing if you really feel nervous. But don't worry I'm sure you'll both enjoy it even if you don't tell him.
Ps: Have fun on your date!
Most Helpful Girl
I would tell him that it is your first kiss because even though I'm only 16 I told my first kiss that it was my first and he actually helped me know how to kiss haha :)