I've found about 45 minutes before park opens works well for us to be at the park before rope drop. Just keep in mind if you just missed the bus to whatever park you are going to ...then will be about 20 min till the next one arrives. We have never had any problem arriving at any park on time using the bus system. And we've stayed at POP, PORS & CSR. We found CSR bus system tops this trip!
Going to other resorts to eat does take more time. As we do it more it does go smoother but it does take time. I try to schedule which places I eat at in ways that makes the transportation abit easier & it works well for us.
For example...Flying Fish on HS day as we can go from HS by boat there. Afterwards we went to the
MVMCP so caught a bus from there to MK. This was our longest wait of the trip.
We went to Cape May breakfast & Yachtmann's supper on our Epcot day & then just walked back to Epcot for transportation back to CSR.
Ohana supper after MK is always easy for us & then we go back to MK & to CSR from there. California Grill the same way.
When we went to Artist Point we left our resort went by bus to MK & by ferry to Wilderness lodge & returned the same way. I enjoyed the ferry rides & this way one of our fastest travels between resorts.
It does take awhile to travel so build in enough time so to not stress out. Mostly just check into the easiest ways to travel from your resort & back to the places you want to go. [Like if you want to go to Yachtmann's or the boardwalk area...exit the back exit at Epcot & walk or ferry there....don't go to the entrance at Epcot & take a bus there...it took forever & yeah..we really did that several years ago!]
The toughest ones is figuring out how to get to a breakfast....they are kind of tough to arrive at on time.