Poinsettia...

...has one little red leaf. The plant's leaves that provide its color through a process called photoperiodism. This process, in response to certain amounts of light or lack thereof, turns the leaves from green to red or pink, white, and other shade variations. 
Help your poinsettia to turn red by placing it in total darkness for 14 hours each day starting eight weeks before you want to display it. During the day it needs bright light.
Let's see what will happen with  my little plant, that I got from Carolinav last year for Christmas. I probably have to follow these recommendations now if I want it to have red leaves again.
So 8 weeks before Christmas will be: 31 October 2021. So guys get ready.