Visited Snowtown Yeti on 23 October, a Saturday, for a pre-season warm-up. They had been open a week, having laid down a ribbon of crushed-ice on their "A" course, served by a quad lift and a pair lift operating in parallel. The quad was ski-on, ski-off, while the pair was walk-on, walk-off. The first lift had a huge line to get on, probably about a 10 minute wait. The second almost none.
The snow quality was, well, what can one expect for October? The point is that it is there, and they are open. At that time of the year, there really aren't a whole lot of other options, of course. Sayama (the indoor slope in Saitama) opens a week after Yeti, and Karuizawa Prince Hotel another week after that. Mid-November, Marunuma Kogen opens. Of these pre-season options, Yeti offers the longest course that I know of (1 km versus 300-400 m at the other places), though it is also much narrower than the others, maybe 6-8 m in width for most of it. So one has to be a little more careful going around other people on the course, but one gets a longer run in the bargain.
The "A" course is pretty gentle, with the steepest bit being 23 degrees, right at the end. The customers were probaby 90% boarders. Staff seemed quite friendly and cheerful. Kima curry wasn't bad, either.
The tickets are not too expensive for the first 3 weeks, 2,800 yen for adults on weekends and holidays and 2,000 yen on weekdays. After the first week of Nov. the price goes up. So really the sweet spot for when it would be worth going there is late October, unless perhaps one happened to live nearby.
Compared to many other ski areas Yeti may not be not much, but come October one can at least see a bit of foliage from the chairlift, watch people playing golf on the adjacent golf course, and wake up one's skiing muscles after the summer doldrums. There are worse ways to kill a Fall day.