Weeks notice with a sign on bonus

I have a sign on bonus that states if I leave before my 1 year anniversary I will be required to pay it back.
I have wanted to leave for quite some time now - the culture and environment that I am working in is horrendous. The job is completely different than what I signed up for and am absolutely miserable. Making it through these last several months have taken a toll on my life and health.

My 1 year anniversary is March 1st. I'd like to give my notice ASAP. If I return from Christmas Break on January 3rd and give notice that my last day will be March 1st am I legally covered? Or is there a possibility they will make me pay the money back? Also, would I be paid through March 1st as well? If not January 3rd, when do you suggest I give notice?

THANK YOU