if you are trying to actually see the show, you'll want to arrive before the last set of the evening concludes. the set start times are usually posted on social media by the bands/artists performing or by the venue itself. i usually find the bands' start times posted on Twitter, Instagram, or Facebook on the day/evening of the show on one of the artists' accounts. it's usually safe to assume that there are breaks between sets.
As late as you want, they stay open after the bands are finished
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