Birthday surprise for my BF

Hey everyone, so my boyfriend's birthday is in two weeks and I planned to surprise him. He has been asking me (without pressure) if I can give him a blow job but I always refuse. The thing is my gag reflex is super strong 😖 and I don't want to make it awkward by trying to barf😅. And it's going to be my first time doing it too. So, can I have some advice, please?

Thank you