Did a search but couldn't find my answer, sorry if this have been covered before...

I received a schedule change notice for a trip in January. I am able to see the options on nwa.com to change my flight. Question is, how long can I wait to make the change? Could I wait until a couple days before I'm supposed to depart to take advantage of the schedule change and pick new flights for that day (ideally flights that are nearly F0Y0)?