Curtain going up - earlier than ever

Philly.com: Empires rose and empires fell, but if there was one thing the world could depend on, it was the 8 p.m. curtain time for theater, opera, and classical music performances. That, however, was back in the 20th century.
In the 21st century, if you don't check daily listings, you may be late for Act One. Though the Philadelphia Orchestra holds steady with music at 8, a weeknight performance at the Wilma Theater, the Arden Theatre, Philadelphia Theatre Company, or 1812 Productions may start as early as 6:30. For Sunday-night touring Broadway shows at the Academy of Music, all traditional bets are off.