Your trip overlaps mine (Dec 3 - 15), so I pulled up my schedule which has all the crowd numbers for each park.
Ok, I see the problem. MK is a 6.8 crowd (out of 10) that first night. Generally, Saturdays and Mondays (because of EMH) are the worst days to do MK. Contrast that with the crowds on Tues (1.1), Wed (1.6), Thu (1.2) and Fri (1.1). Now some of those are low because of closing early with
MVMCP. I'm assuming you want to do at least one non-party day at MK so you can see the Electric Light Parade and regular Wishes, so that leaves Wed.
Here's my thoughts - I've been to MK recently on a 6+ day. It was actually our arrival day also so we arrived late. I thought with a good plan, we wouldn't mind and I really love to do MK first. I was wrong. I would never do that again if given the choice. You can get so much more done on a low crowd day that the extra hours don't matter. I would definitely recommend going to MK on Wed to see ELP. Even if you only went half the day and went somewhere else in the morning, it would still be better than going on Monday.
Now, having said all that - if you're not planning to ride a lot of rides and you do the Dessert Party so you're not fighting the crowd for a viewing spot, then it's more feasible. It really depends on what you want to accomplish that day.
I would hit Epcot (1.1) or DHS (3.3) on Monday. Also, although only one Fantasmic is listed at present, there's a decent chance there would be an 8pm Fantasmic that night as well.
Do you have something booked already for CP? If not, double-check to make sure there's still availability. You may not have a lot of options at this point. Same with FDP; I called on my 180+ and still couldn't get the one I wanted. I think Ohana books fast too, though I've never done that one.
Other than that first day, I think the rest of the plan looks great. We're scheduled to be at AK on the 13th too. And the 14th is our Vote Day so we might be at MK.