Hokkaido, Tokyo trip itenerary. Doable?

I'm planning a trip to Japan in January to Hokkaido & Tokyo. I've been to Tokyo many times but it'll be my first to Hokkaido. I've booked my flight tickets and i'm planning to get a 7 day JR pass. When do you think is the best day for me to activate the JR pass? And do you guys think my plan below will work? Thanks!

Day 1 - Fly to Narita. Take domestic flight to Sapporo. Check in to hotel in Sapporo.
Day 2 - Otaru
Day 3 - Sapporo
Day 4 - Leave Sapporo in the early am. Take train to Hakodate. Stay 1 night.
Day 5 - Leave Hakodate in the early am. Take train to Aomori. Stay 1 night.
Day 6 - Leave Aomori. Take train to Tokyo.
Day 7 - Day trip to Karuizawa
Day 8 - Day trip to either NIkko/Kamakura (not decided yet)
Day 9 to 11 - Around Tokyo.

Day 4 looking at your current schedule.

Your plan looks fine, but I'd leave Hakodate a bit later in the morning so that you can at least see the Hakodate Morning Markets.

Enjoy your trip!

Great! Thanks very much GC3 for your input.

Note that you could save a bit of money by using your JR Pass and taking the train from Tokyo up to Sapporo on Day 1/2.

I'd probably also consider splitting your trip up unless you have specific reasons for doing it in your original order.

ie. Narita - Tokyo - Aomori - Sapporo - Hakodate - Kariuzawa - Nikko - etc.

Would save you needing to pay for the domestic flight from Tokyo to Sapporo, and helps break up some of the longer train trips too.

I initially thought of using the JR pass to travel up to Sapporo. But managed to find a relatively cheap one-way domestic flight with Jetstar for only 4990yen. So i decided to fly there to save some time as well. Thanks for your suggestions.

Nice find! Sounds perfect then.

If you intend to spend a whole day in Sapporo, do it on day 2. Activate your rail pass on day 3 for the daytrip to and from Otaru. It will cover your rail journeys till day 9. In Tokyo you can still ride the Yamanote line with the rail pass for free.

But to fully utilize the rail pass and since you had been to Tokyo before, consider cutting short you stay in Tokyo and spend one night en-route from Aomori to Tokyo. The Tohoku region has so many worthwhile destinations that it may be difficult to single out one particular site, but if you haven't been there before Sendai would be a logical and convenient choice.