The average reported time is 70 minutes. Let's say it takes you 90 minutes. Assuming your flight arrives on time, that puts you at Pop at 10:30 a.m. Check-in could easily take 15 minutes, and if there's a decent line it could easily take 30 minutes. Let's say 30 ... it's now 11:00 a.m. You walk to your room, 10 minutes, and then 10 minutes for bathroom breaks and whatever ... it's now 11:20 a.m. You get to the bus stop by 11:30 a.m.
Let's say the MK bus is just pulling away as you walk up, so you have to wait 20 minutes for another one. It's now 11:50 a.m., and you get to MK by 12:10 p.m. if there's traffic. You get to the MK turnstiles at 12:15 p.m. By the time you walk down Main Street, see the Castle, and wipe away a tear, it's 12:25 p.m. Sounds like lunch time to me!
I didn't present a worst-case scenario, but I did present a pretty conservative one ... you could make it there 45 minutes earlier if the planets align just right.