Everywhere I look people have a different answer for this! I figured Scrappy and MrHub just got back from the Poly, so maybe we'll get a definitive answer here 
If I have an ADR in the Magic Kingdom at 8:00am, will the resort monorail be running at 7:30 so that I can get there on time?
I don't know the exact times, but it's always run early so people can get to parks before opening.
Wishin' I was at WDW!
Everything I have ever heard is that ALL Disney Transport starts running two hours before park opening.
Bella
What's crazy is I've asked CMs this and gotten different answers. You'd think this would be an important bit of knowledge.
I would have to think yes, Annie, but I don't know for sure. Surely the concierge at your resort could confirm?
Cdub - YES. In fact, a monorail CM sent us totally out of our way a couple of weeks ago by telling us that a bus went from TTC to DD. They were super-wrong, and DH was super-unamused when we had to walk back to the Poly, after we had ridden the monoral ALLLLLLLL the way around from there to get to TTC. Sure, I should have had more sense than that. But you think they know what they're talking about.