Itinerary Advice – January in Japan

I will be in Japan from January 3, 2024 to January 21, 2024 and wanted some tips on my itinerary. I haven’t completed it but I’ve got a few things laid out already.

I arrive at Haneda at 3:25 PM on January 3 and connect onto the 6pm to Chitose. Both flights are ANA but I believe I will have to go from Terminal 3 to Terminal 2.

I depart Haneda at 4:25 PM on January 21.

One of my main goals for this trip is to experience beautiful snow. We had a snowless winter in New York City this year, so I’m of course going to the snowiest place on the planet to make sure I get snow this time. In that matter, I’m hoping to ski at Sapporo Teine on January 5 and at Zao Onsen on the 8th and 9th. I also am hoping to spend a night at Ginzan Onsen and visit Noboribetsu on my way from Sapporo to Tohoku.

I’m also looking to get as many neat and interesting trains and train routes in as reasonable. On the itinerary I already have the Resort Shirakami, as the Gono Line is one of those stunning views you can’t miss. I’m also hoping to work in the Sunrise Express and some of the old former JNR trains in west Japan if they’re still around by the time I go.

Right now my itinerary is as follows:
Get into Sapporo on the 3rd
Do Hatsumode and explore Sapporo on the 4th. Odori park, the Sapporo Beer brewery, and the view from the top of the cable car are among the things on my list there.
Ski Sapporo Teine on the 5th
The 6th gets a bit more complicated:
7:30 AM Suzuran from Sapporo to Noboribetsu arriving at 8:15 AM
Visit sites in Noboribetsu for a few hours such as the bear park, the Ainu village and Jidokudani.
3:55 PM Hokuto to Shin-Hakodate-Hokuto connecting to a Hayabusa departing at 6:40 PM getting me to Shin-Aomori at 7:44 PM and Aomori by local train at 7:56 PM.
The 7th is also somewhat busy:
8:09 AM Resort Shirakami to Akita arriving at 1:26 PM.
From there, Komachi to Sendai, Yamabiko to Fukushima, Tsubasa to Yamagata and then bus over to Zao Onsen
I plan to ski at Zao at least on the 8th and possibly also the 9th before spending that night at Ginzan Onsen.
From there, on the 10th my much less detailed current plan takes me down into Tokyo for a few days, then out to West Japan by Sunrise Express before returning back to Tokyo on the 19th, possibly going to Hakone on the 20th and flying home on the 21st.

This will be my third and longest trip to Japan having previously visited in April 2018 for sakura and January 2020 for Love Live Fest.

A few questions:
Where would be the best place in Sapporo for Hatsumode? Can I wait until the 4th or should I go when I land on the 3rd?
Are the bear park and Ainu village worth seeing in Noboribetsu?
How far in advance should I reserve accommodation at Zao and Ginzan? I know those are both very popular places to visit.

The latter half of my trip is still wide open. Should I plan more time in Tohoku and cut some of that time in other parts of Japan?

Thanks for your input.