There are a total of 7 bucket lists in this DLC. Each completed bucket list gives you an additional star.
When you start the DLC only 2 bucket lists are available. If I remember correctly it's #3 Dash Through The Snow & #4 Smash Snowmen.
If you want to get this quickly I suggest #4. You have 2 minutes to smash 20 snowmen. Very easy. Can be done in less than 1 minute. Especially with all assists turned on.
The other bucket list challenges unlock with the main story. Earn stars in the events and you will soon unlock all of them.