Trying to figure out if I should take a PRN job??? I already have a full-time job..?

Okay so I just transferred to my current job, I've had the job about 2 weeks now. My new job is a guaranteed 40 hours a week, I work Tuesday-Friday 6:30pm-4:30am, pay is great. Full benefits and not too far away from home. I'm planning on moving closer to my job next month. So yesterday I get a call to come in for an interview on Monday 3/24 at a hospital about 1 hour away. So I'm trying to figure out if I should go to the interview or not. It would be as a Medical Laboratory Technician, but the position is PRN(which means pretty much "on call", when needed). I haven't worked as an MLT yet, but have been waiting for the opportunity since August 2013. I'm having a difficult time with figuring out what to do. I'm thinking maybe I can go for the interview and see what happens, and if I get the job, I can ask if they are willing to work with me since I have a full time job already. Any suggestions???!!! I need to make the decision pretty much today........