@AlyssaBlue: they do seem to start blooming simply because days are shorter, here it's completely dark at 5:30pm nowdays
Mine started forming tiny hints buds on its own and that's when I started putting it in the closet - simply because I keep my plant lights on quite late and I didn't want that to discourage the cactus. It still knew its winter though, they're smart
BTW, it's not the first time I got a comment on the "uprightness" of this cactus, I like it a lot too. I kept it well watered through the summer and in very bright light - South windowsill, it was a bit floppy and bone dry when I bought it but with more watering, it got the more upright position and grew nicely too. When I noticed a hint of buds I started letting it dry out before watering - but moved it to a room with a grow lamp and a humidifier (due to winter). I don't know if any of that mattered but it seems to be doing very well so far.
I have moved and rotated this thing so many times I can't count, also repotted it twice, once to a much larger pot for it to grow and soil not to dry as fast, and then again to a bit smaller terracotta pot for it to be dryer for flowering. The only thing I don't do when repotting is messing with the rootball and the soil in it. It's a pretty hardy plant once it has its water and light to its liking, one of my favorites!
