Welcome to the world of punting. I am sure you will have a blast.
As for choosing a whore to enjoy your first time in, that is quite a difficult question. Part of me is tempted to simply say choose someone who you fancy and who is reported as giving great service. Raven, Eva, Kelly, Natalia at Portfolio would all meet that criteria. I'd be tempted to tell them it is your first time and let them take the lead. I get the impression that maybe Eva or Natalia especially are intelligent and experienced enough to ensure you have a good time.
Top tips:
It is not a date. It is all about the fucking and sucking. You are hiring someone to get you off
Regular STI testing is strongly advised. More info elsewhere on this forum
Make sure you review
Don't overthink things. Just get in there and have fun
All the best