I would wait until 60; you can run BRS/Scholo if you're out of quests. I've found it really makes Outlands way easier to start two levels later. You never run out of quests, and usually end up with Netherstorm/SMV barely touched. That translates into a pretty ridiculous amount of XP-to-gold conversion.

Edit: It's a lot easier if you're starting from scratch; if you plan it out, and work through two newbie zones, you can get enough of a quest buffer by level 20 to last you the rest of the way to 60. You can do yellow quests nonstop, skip gathering stuff, and still have a zone leftover at 60.