Should I just use points for purchases from now until the end of the year?

First off, I am a hoarder of points. I like to use them on things I wouldn’t normally buy for myself. I have to make another purchase this year for some Christmas presents and was debating on using the point multiplier and the 20% off coupon or if I should just use points with the 20% off coupon. Does the money I spend now help maintain my diamond status for the following year or should I just use points? I’m already diamond for 2026, but will the purchases I make now help towards being diamond in 2027? I hope my question makes sense!