When you check in at hotel make sure you get your Hoop Dee Doo tickets there; that will avoid having to stand in line at FW to get the tickets. Also make sure you get your pass to put in your car window for parking.
If you leave CBR by 3, you will have plenty of time to get there by Disney transport. One way would be bus to MK and then boat to FW. By Disney transport, it can take an hour at that time of day but probably not more than 1 1/4 hours and could be as low as 45 to 50 minutes (a lot depends on how long you need to wait for a transport). Note, they just recently announced that FW is going to have direct transport to MGM and Epcot (used to have to switch at TTC). Not sure when that will go into effect but if it is in place by time you arrive, you could also bus to MGM and then catch the FW bus there (MGM is less than 1/2 mile from CBR entrance).
If you drive, the shortest route is as follows:
Exit CBR and turn right onto Buena Vista Drive, go to Bonnet Creek Parkway (about 1/2 mile) and take a left. Take that road till it ends and take a left onto Vista Blvd. You will come to the back WDW gate where there is a guard who will waive you in if your car has that pass. First right thereafter will be FW parking area. From there you need to take an internal bus to Pioneer Hall (the parking lot is on the north end of the property about 1 1/2 miles from Pioneer Hall and internal busses come regularly to the parking lot bus stop. That car trip will take about 5 to 10 minutes. The internal bus trip adds another 10 to 15.