We did it from Kissimmee with sat nav in 70 mins last year. Best time without Sat Nav is approx 80 mins but it depends on the traffic.
We normally try and go on a Monday as even during the summer its not that busy compared to some of the parks in Orlando. We walked onto most of the rides and the longest we queued for was about 10-15 mins for the log flume. Weekends can be busy as you get more locals there.