Good morning,
We just got back from the Shades of Green. The buses start running at 0730. We wanted to get there at 0730, since we were doing EMH at 0800, so we took the Shady Shuttle, which is an informal jeepy kind of thing. You can't order or reserve it, but you can frequently catch it in the morning. It's a large golf cart. We hopped it to the edge of SoG property, then walked to the Poly to pick up the monorail.
It's not a long walk if you can't get the jeepy, but I'd allow ten extra minutes for the walk.
The SoG buses run every 15 minutes to the TTC, but only once per hour to the parks.
Let me know if you have any other questions about the shuttle service. BTW: Watch out for the dining hours. We didn't find them convenient for our touring. Other than that, we had a wonderful time. I asked for an 'early check-in', and they had a room ready at 0900 on the day we arrived! Now THAT's an early check-in!!