Well I would put all the layers in the begginin’ of the comp.
Hit CTRL+A to select all.
Hit ALT+SHIFT+T to add a opacity keyframe. Hold ALT+SHIFT and hit the right arrow key 6 times to move those KFs 2 seconds ahead. Set another keyframe at the beggining, this time changing it´s value to 0%.
Then go to the end of the layers. Hit ALT+SHIFT+T to add a opacity keyframe. Hold ALT+SHIFT and hit the left key arrow 6 times to move those KFs 2 seconds back. Again set another keyframe at end, this time changing it´s value to 0%.
Then right click any layer and chose keyframe assistent>sequence layers
Then chose the right ovelap value.
It´s the easyest way I can think of and I do it all the time. If the clips are of different lenghts you can go to the last one and hit CTRL+A then ] to align them all at the end before setting the out opacity values. Then back to the beggining and hitting [.
Act like a robot and it all will come out nicelly.
Hope I was of some help.
Cheers.
ninguem