Fantasmic is a 25 minute show, depending on the attendance and where you sit, it could take 15 minutes to get out of the fantasmic arena, then time to exit DHS... Factor in transportation time to the contemporary from DHS. I think you will be pushing this. I've done these marathon changing parks to hotels to get to an ADR before and what I've found is that I don't enjoy the show or whatever I was doing right before the sprint starts because I am watching my watch and getting frustrated with slow vacationers enjoying their trip. Lol...don't they all know I am trying to get to an ADR across the world in 15 minutes.
So, a few things to consider here.
-try to get a later ADR for CM or work it into another day
-is there another night that you can see fantasmic?
-stick with your plan, enjoy fantasmic, get to CM when you can (accepting that you might be late), and plead ignorance when you check-in at CM. Begging forgiveness that you didn't realize it would really take 2 hours on Disney transportation to get there.
In our experience at CM, if you have an ADR, you will get in, unless you show up ridiculously late. We've had ADRs there and still waited 30 minutes to get seated. We've also not had ADRs and waited 15 minutes on standby to be seated. And, we've also not gotten in without an ADR. We've been up to an hour early to ADRs and up to 30 minutes late for ADRs...Cast Members are very used to this and are mostly understanding.
But, since you are 80 days out, I would try for a later ADR or a different arrangement. CM is very easy to do in a Magic Kingdom day, so without having to restructure your entire trip, maybe there are other options so you can enjoy both with plenty of time to not feel rushed.
Good Luck and how exciting for this to be your first trip!!
