We did it 2/13 of this year. We were actually staying at Kidani, and there was either an extra flyer in our checkin packet or it was on the scheduled activities sheet, not sure. I know we did need to rsvp.
We weren't really thinking about it, but then we were at MK that day, did a bunch in the morning, had lunch at CRT, and then just sort of lost the will to be there at MK. Noticed that the timing was decent. DH found the closest DVC kiosk and they were able to sign him up (I think they called over? not sure), we got out of the park, found a cab, and went over to Jambo.
DS had the BEST time in the childcare spot (which was the slightly downstairs area with drumming and some activities), DH and I got to play with grownups and have little snacks and beverages, and we didn't win the drawing (sadness). It was fun!