How can you have no memory of that?! :P If you scroll your mouse down a little, you'll find it!
TRH happens on 3031 AF (4 Yt). According to the Timeline Orllewin falls at the end of that year and The Fall of Calibus takes place before that.
Perpetual Doom is placed on Spring (ever since Harold didn't want any more rises, in which it is mentioned to be March). Thingguy says in SA "almost fifteen years". That means that fifteen years are not complete during Scattered Ashes. This is not what I was leading to, but I just realised while writing this that my Timeline is wrong. The way the Timeline converts from AF to Yt (3027 AF being equal to 0 Yt) means that the numbering of Years of thedude signifies how many years are complete since thedude's conquest of Morcia and not which is the current year being completed. That means that in this system the year called 15 Yt, is 15 (+ a number of days) years after thedude's conquest, 15 complete years. So, it's actually 1 year after the beginning of SA. In other words, SA happens on 3041 Yt, not 3042 Yt.
There are two ways to amend the Timeline. The simpler way would be to change the final date to 3041 AF (14 Yt). In that way, nothing else would have to be changed in the timeline (avoiding some possible confusion). However, it may be considered confusing as well, as this is not the standard way people think chronologies and dates with. Indeed, I'd prefer to use the second way, so that it may be the same style as all other calendar systems (like the 20-eth century is the century that ends on 2000, the 15th Yt would be the one ending 15 years after thedude's conquest instead of starting 15 years after it). The second way would be to make 3027 AF equal to 1 Yt instead of 0 Yt, in that way having to add 1 to all Yt chronologies mentioned as well as change 3042 AF to 3041 AF. What do you guys think? Let me know if I confused you.
Returning back to the original topic, in the unreleased SA chapter I've written, it is mentioned to be Fall (accounting for the fact that we're halfway through the fifteenth year). That would mean that if TDD occurred anywhere between Spring and Fall (1-6 or 1-7 months earlier, depending on SA and PD's accurate dates) it'd be the Year 3041 (previously what we thought of as 3042). For anything longer, TDD's year would be 3040 (previously thought of as 3041). It could also still be happening around the 10th year (3036? AF), but a final decision has to be made now.