Another data point I have is I signed up on waitlist for an October SQ306 SIN-LHR on J saver, at the start of this year.
Why? As was speculated back then this was going to be the inaugural route and flight for the new J product and I felt like having a go at getting an award seat.
Couple of weeks ago the fateful news dropped that new J product has been delayed to 2027, so no chance of SQ306 in October having the new product anymore. And voila what do you know only a few days later an email from SQ - your waitlisted flight is available for confirmation