It is December. There are just two weeks before finals week. Does that mean six class times together?
Obviously your painting is your priority. This should be enough time to finish it, so look at the rubric online, and plan to turn it in during finals.
Regarding your sketchbook, though, I still want you to be working in it with an eye towards quantity between now and the end of the semester. Even just a few minutes each day is amazing. I will view them while you work on your paintings (likely) more than once before the semester is over.
For now, if you want some inspo, consider the below.
It is very likely that you will see at least one of these in the future, but for now I wanted to throw out a few different views of animal images. Not because I want you to copy these, but because they are very different ways of looking at the same topic/prompt/idea.
If you are stumped as to what to do, you might use one of these ideas as a jumping off point.