If you buy October today (if it’s available), you will get current UY points for October 2021. If you buy December today (if it’s available), you will get December 2020 points since that is the current UY. However, if you buy December on December 1st, you will only get December 2021 points and not 2020 points since, by then, the current UY will have changed to December 2021.