Two weeks ago, we stayed at OKW. We got on the buses at the Peninsular stop (1st stop) and it consistently took approx 15 minutes for the bus to leave from OKW (which was nice to know in case we just missed our bus, we could walk up to HH).
From the time we left OKW, it took 10 - 12 minutes to get to MK, and about the same to Epcot and MGM. It took about 20 minutes to get to AK.
FWIW, many of the buses now have clocks onboard - digital displays mounted behind the driver.
Just our experience. YMMV (or YTMV - your time may vary).