It's never taken us less than 90 minutes from getting off the plane to getting to the resort. The commute itself is 30 minutes alone - factor in traffic, the waiting time on the bus for it to fill up, as well as any line you may face at the DME area. If you're arriving on a weekend, expect a line - took us a good two hours when we arrived on a Saturday morning once.
After you arrive at the resort, you don't necessarily need to check-in first unless you want access to your dining credits. Otherwise, you can either store your carry on bags or head straight to the bus to DTD. Will take about another 20-30 mins to get to DTD from your resort.