if you are using disney transportation Chip and Dale( bus driver at disney) recommended leaving an hr for travel time and we have found that to be pretty true. even though the drive time is probably less than 10 mins, you never know if you will need to wait for a second bus, what ever.
we went from Mk to Ohana 45 mins pre adr once in off season and cause just as we got to the dock the boat was full, we had to wait for another boat and were almost late.( maddening cause we could see the poly the entire time...so near and yet so far!)
they will hold your adr for 15-20 mins( at least that's what they told us)
to get back the best way is go to an open park close to your resort ( mgm or epcot in this case probably, unless ak happens to be open still) then get on a bus from there to yur resort. other alternative but it seems like it takes longer is go to dtd then get a resort bus there. that 's way out of your way though. if you can pick a park not ready to close that is better as at closing you might have to wait for a bus as there will be lots of people leaving so i'd probably go to epcot if i were you