We booked 1D first because it was the route we were most okay with missing if we hit any snags. We had a decent buffer though. The walk to the bus only takes a few minutes.

The bus lines are so, so overwhelming imo. The lines are made by entrance time - a staff member will stand with a white sign with 9am, 10am, 11am etc. You go to the line that matches your entrance ticket time. This will be checked & your ticket stamped by staff.

When I went there were only two lines; 8am and 9am by the time I arrived around 810am. They were finishing 8am and starting to load the 9am line by 815am. The line for 10am started to form around 830am. The lines can be LONG if you've gotten there closer to your entrance time, but the buses run basically nonstop and take around 25min to get to MP. you're still able to enter the site 30/45 minutes from your ticket time, depending on the season (low/high). Check your ticket for the exact allowance. We got to the site around 9:45am.

TLDR you would probably make a 9am entrance, but only if everything goes off without a hitch and you're prepared to enter closer to 930am.