It says the Purge comes out on July 4th but I see a showing time at 7pm tonight, is that accurate?

Yes normaly they have preview showings the day before it technically comes out

The purge does come out tonight. Basically there is always showings a day before the "Release Date"

Yes they have early premiers before the actual premiere

Yea, the have a premiere night. Usually the day before at 7, most the time theyre sold out, if its a major title.