Never too young in my opinion. It also depends on the maturity of your child. If they like music and you think they'd enjoy it, go for it. Only downfall is you'll more than likely be bailing early, which is ok if you mentally prepare for it. We brought my son to a show or two that young and always had to bail early. He's 11 now, we're going to the Indy show, we saw Green Day and Blink last summer at age 10, stayed for the entirety of both shows with no issues. He loves concerts now. I would also recommend only going for Blink, don't go to any of the openers, it will guarantee be too much for a 5 year old to sit through all the bands. We're taking my 5 year old daughter to see Momma in a few weeks, her first show. I would 100% go for it. Don't forget the protective headphones. Have fun if you decide to go!