There are many "rules" governing this depending on the body of elders, carla.
If a JW buys Christmas cookies after Christmas that is okay.
If a JW eats Christmas cookies after Christmas that is okay.
If a JW takes Christmas cookies before Christmas and waits until after Christmas to eat them, that is okay.
If a JW takes Christmas cookies at work before Christmas and no one knows they are a JW or no JW sees them, that is okay.
If a JW only eats the cookies that look like angels or bells but avoids the Santas, wreaths, and Christmas tree shaped ones, that is okay.
If a JW is given Christmas cookies, that is okay because while JWs can't give Christmas gifts they can accept Christmas gifts from others. (Question from Readers)
If a JW has a non-JW husband, they can even make a holiday meal at the request of the husband, including Christmas cookies. (Question from Readers)
If JWs get together on Christmas Day had have the same food that non-JWs are having, they are not celebrating Christmas, just taking advantage of an opportunity when everyone has the day off. But of course non-JW family will not understand why they can do this but not come to their homes for a meal on that day (except for JW sisters with non-JW husbands who request that they go).
I'm sure they are many more hypocritical "rules" that JWs use to dance around the Christmas customs.