Hi James --
You can do this by using two cues to play your "next track". You would use the first cue to play the portion of your track prior to the fade out, then auto-follow to continue playing your track in the second cue, with Stop Others to fade out the initial track you have playing.
Let's say you want a 3 second delay after your GO before the first cue begins fading out. Add a cue with your media file, set the End Time to 00:03.000, and enable Auto-Follow. Then add another cue that uses the same media file. Set the Start Time of this cue to 00:03.000, turn on Stop Others, and set the Stop Others fade out time to the fade out duration you would like.
This way, when you start your next track with a GO, the first portion begins playing and automatically auto-follows into the second portion, at which time Stop Others will take care of fading out the first cue that is still playing.
Brent