What Should I Do...

I have a surprise for my boyfriend but I am horrible at keeping secrets, especially from him! I really want this to be a surprise. I bought us concert tickets for this Saturday night to a concert he really wants to go to(He never reads my blog so he won't find out through this.). The problem is I just found out that he has to work Saturday night until 7 but the concert starts at 7:30 so I don't know what to tell him because I want him to get off work early so we can get a decent parking spot downtown(which I hate driving in the city as it is! I always get lost or get pulled over!). He's never been to a concert either so I want to make sure we get there in time so he doesn't miss anything. I was wondering if anyone has any suggestions?? I've already asked him to try to get off early because I wanted to go out to eat but that didn't really work. I really want this to be a surprise for him because he never thinks I can pull off surprises! If anyone has a really good idea, let me know! I would really appreciate it!