It's a bit longer with kids, but 5-10 minutes is a good range.
If you're planning on walking, you can request a treehouse "near the pool" in the checkin tool and that will get you near the walking path (and boat dock). With that said, the good thing about the Carriage House stop is it's the first for the parks so the bus will have room. The bad thing is you're going to spend another 15 minutes or so going to the other bus stops in SSR. Usually when we have a THV we rent a car and drive to parks other than MK. (and if my planning fu is good, that's also a trip we go to Universal)
Bruce