When is the best time to put a Christmas cactus in the dark?

Here you go!

https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/advice-for-christmas-cactus-care.htm

Maybe it isn't too late!

For the month of October, put them in a dark room for 10-12 hours a night for 4 weeks. Make sure during the day, they get bright light, but no sun. Water as usual, about once a week is sufficient. In November, if you notice any small phyloclades (tips), pinch them off. Toward the end of November, water well and then one week later, give it a very good 'bloomer' plant food, such as Miracle Grow 15-30-15 full strength. The next week water well and then give it one more good dose of the bloomer. They will begin developing buds on each tip and bloom for you at Christmas. They absolutely have to have the dark-light cycle.

Put it in the dark in November to try to force flowering in December. The best season my old Christmas cactus had was when it started blooming in November and kept blooming through March, with a full plant with flowers. Two years later it was dead. 😇💞

You do not have to put a Christmas cactus in the dark to get it to bloom. Less watering during the summer months usually forces it to bloom. Once blooming, then water more often. I have one that is starting to open the buds now and will probably bloom until April. You may try a little liquid fertilizer in the water about once a month while it is blooming.

http://balconygardenweb.com/how-to-make-a-christmas-cactus-bloom-at-christmas/

All l do is move it from the window to the other side of the room. It was move 2 weeks ago. It already has flower buds covering it.

Thanks for all your help. I have this issue resolved.

Your help was very much appreciated.