You are right to be confused
Your footage is trimmed. in the tutorials you watch they are not. Mocha Shape data contains full data from the first frame of the original footage (even though it's rather useless information) and not from the first frame of the trimmed footage (like mocha tracking data). so when you export shape data from Mocha to Ae, you should paste it at the first frame of the original footage and NOT the trimmed footage.
Btw this behavior is fixed in V5 (only Mocha pro)
Now, your composition contains the trimmed footage and you are comfortable with it the way it is... so how do you paste key-frames at the beginning of your footage when you don't see it in your composition timeline?
1. press twice on the footage layer in your timeline, you will then be at the layer window of that footage
2. press home key to go to the first frame of the actual footage
3. now go back to the Composition window. you will not see your CTI because it's earlier in time
4. make sure the layer is selected and choose edit-> "paste mocha mask" for a mask or Ctrl v for mocha shape
5. get thrilled with satisfaction and vote Hillary!
i found that even if i were to start in the right spot of the video, when i copy and paste the mask...only the first frame of the mask is copied and the frames following that all just use the same mask from the first frame....as oppose to what we obviously want, which is the tracked masks for each frame that follows the head
any ideas? in the tutorials the masks followed the head and i did exactly what was done there
since there are so many things that could go wrong when crossing between Ae and Mocha, either by wrong workflow or even a bug or something wrong with the clipboard, I suggest any of the following:
1. upload your footage and specify which range of frames do you want to roto out so I can try for myself. you can upload your aep file, your result mocha file or just the footage, but the footage needs to be in there.
2. record what you are doing so we can examine your workflow step by step