My first concert was QOTSA in SF a month ago and honestly there was a line out the door. Bands usually have timings posted for their shows--when doors open, when/who is opening the show, etc--usually a day before or on the day of. If you wanna buy merch, I'd suggest arriving before doors open so you're able to cop merch before they're sold out. Also if you have GA and wanna get to the front by the stage, make sure to get there as early as you possibly can. For the QOTSA show, I came back as soon as doors opened and I missed the merch stand but we stood about 10 feet away from the stage (was still a great view though). I'm planning to see the Foo's here in San Jose in September! Have an amazing time!!