I have a job interview coming up...should I mention an upcoming trip I'm taking?

Hi. I really, really want and need this job. It's a CNA position at a local hospital. I'm wondering whether or not I should mention the trip I'm taking next month. I'll be out of town for 4 to 5 days because my boyfriend is in the National Guard and is deploying to Afghanistan soon, and he gets a four day leave and wants me to be there. He already booked a hotel room for me and everything. Should I mention this during the interview or should I wait to tell them if I am hired? I don't know what to do :(