During my misspent youth, I covered a lot of concerts and with the experience gathered; I can proudly say that i know when to fire my shutter. Taking photos at a concert with out the use of an external flash is hard to do.
You do not want to have the flash fire and blindside the performer. A big no-no in my books. What I normally do is to listen to the latest album of the artist performing to have a feel of their songs, from there I can tell me 80% accuracy of where the performers will be and how the strobelights will strobe.
This is how i do it, it may work for you.
Always Keep Fighting And Never Lose Hope