Placing layers along a path

The no brain way:

1. Draw your path with the pen tool as a shape layer or a mask
2. Set a single keyframe for the path and cut it (Ctrl/Cmnd + x) to make sure that it has been copied
3. Select the layer you wish to distribute along the path
4. Press Alt/Option + p to set the first position keyframe and then Paste (Ctrl/Cmnd + v)
5. Repeat 3 and 4 for all paths but move the CTI for each new layer
6. Slide the layers or the keyframes in the timeline to distribute the layers on the path the way you want them
7. When you have added a motion path to all layers and adjusted their timing select them all and press u to reveal all keyframes
8. Drag a selection around all position properties in the timeline and click the stopwatch on one of them to remove the motion and adjust the in and out points as necessary

That is probably the easiest way. 

Another option would be to use the Create Nulls from Paths script to create a null that follows a path, shift + parent all the layers you want to distribute along the path to the null so they all jump to the position of the null at the start of the timeline, then scrub through the timeline and turn off parenting one at a time when the layer reaches the right spot on the path. This option might be a little less work.