Well, if you don't mind an outside perspective there area few places that make more sense than others to "rise". Heartgouger Tower, Sulvan's Fury, Cridan, the Nighthawk Grove, the Sharxian dragon graveyard, the Gelded Halls (which is my recommendation, see below), and the Celerese portal are all focal points for magic or at least eldritch occurrences, as are Tzalteclan, the Seaborne Confederacy, the Holy States, Kemuliaan, and the UJR.
So, on your list of most sensible players, that's:
TheDarkDM (me) in Tzalteclan, which is applicable thanks to Tzalteclan's blood sorcery and the rule of immortal dragon kings.
Snowfire or zabbarot in the UJR, which is applicable thanks to their strong connection to the spirit world which has resulted in prophetic powers and limited teleportation.
HalfTangible in the Holy States, which is applicable thanks to its cryomancers and rule by ice-magic using priestesses.
lt_murgen in the Seaborne Confederacy, which holds the Nighthawk Grove which is sacred to Kina and the source of her chosen, who have shadow magic.
QB (Crima) or DurkBlanston (Caercia) in regards to Cridan, which just spawned the Bale Horse, so probably not the best place right now.
Elemental in Ashenia, which has just retaken control of Heargouger Tower from another mad wizard.
necromancer in Kemuliaan, a cursed desert land ruled over by undying mummy kings.
The Blue Guard in the Sharixian Republic, which holds a gargantuan dragon skeleton from ages past which has played host to some spooky apparitions.
Logic in Celero, whose exploration of a mysterious portal is a harbinger of doom, again probably not the best unless you want some major baggage just starting out.
QB (?) in Sulvan's Fury, whose underground region has produced no shortage of horrors over the years, again likely giving you tons of baggage.
QB in Ahmeskharras, which recently unsealed an expansive necropolis known as the Gelded Halls only to lose some of their explorers in the deepest levels. This is my recommendation if you want to start in an established nexus of weirdness, as the culture in the area holding the Gelded Halls was intensely tribal in a way that would mesh with a lost tribe of witches, and whose taboos against disturbing the Gelded Halls may have to do with an ancient curse that has only recently lifted, giving you a ready made explanation for how your coven is showing up now.
Or you could choose to show up in a place without a ton of foreshadowing and do your own thing, which would also be cool. But that opens the board to every region, so I thought I'd try and help and narrow down your options.