The phrase "week countdown" means counting down the days until a particular event or deadline happens, focusing specifically on the span of one week. Full definition
With a 2 week countdown now in progress and everyone home for the holidays with the rush of places to go and people to see you always want to be looking your best. (sophieandtrey.com)
Can you believe we are in the one week countdown until Christmas?! (girlmeetsbowblog.com)
So I am officially on the final week countdown of my whole 30 you guys! (ladyinviolet.com)