There's a few unknowns at this point, so it's a little hard to answer. For example,
Genie+ and LL are supposed to be available by then, and if you purchase those, you probably won't need to worry about getting on everything you want at least once. It will be interesting to see how the actual experience shakes out by then, what it does to standby lines, etc.
I agree with gelatoni, that I'd probably start 3 days in
Disneyland. There's more to do, and more that is likely to have higher wait times later in the day.
The other thing, and I hope others chime in on this, is that you might want to reconsider one weekend day. In the Before times, Sunday was often surprisingly better, crowd-wise, than Tuesday. It depends on what shows and parades they may have brought back by then; in January you will likely only be able to see those on the weekend, i.e. Friday, Sat., Sun. Those will be fireworks nights; and if the fireworks are cancelled due to high winds or inclement weather, it gives you more opportunity to try again another weekend night.
Good luck, and keep an eye on these boards for when Genie+ starts, to see how that's affecting things and whether you'll want to purchase it! I hope you have a wonderful trip!
