Like, all the other Prologues to Chapters (and Orsinium, which is pretty much a Chapter before anybody thought of designating some DLCs as Chapters) have things that start them off. Sometimes multiple things.
For instance, Stuga will chase you all over Davons Watch, Daggerfall or Vulkhel Guard, for Orsinium.
Or you can run into Alessio Guillon in most of the game's inns, to start off "The Missing Prophecy" for Morrowind.
Or there's the Order of the Eye Dispatch in most Mages Guilds, including some fairly unlikely ones, to start "Of Knives and Long Shadows", for Clockwork.
Vanus Galerion hangs around the major Mages Guilds to start off the Summerset prologue, "Through a Veil Darkly
"Cyrodiilic Collections Needs You" note will direct you to Concordia Mercius - who is also standing around with a quest marker over her head - for Murkmire's "Ruthless Competition".
Abnur Tharn can be found in various places to start off Elsweyr with "The Demon Weapon". Kasura hangs around in inns specially to start off Dragonhold with "The Dragonguard's Legacy".
Either Lyris Titanborn herself, or a messenger who points you to her, is available in starter cities to start the Greymoor prologue, "The Coven Conspiracy". And the House Ravenwatch Contract points you to Gwendis, to start off Markarth with "The Ravenwatch Inquiry".
So where, IN GAME - not in the crown store - does one start off the new Blackwood prologue? I know what UESP spoiler site says on the matter, but this is not currently the case, so please verify that your information is current before you answer?