Talashia, I think, would have started out on her own, on the road from Magnimar.
I will say she met up with a caravan while traveling and was invited to come along with them. Other PCs could have been with them too. Then at any point along the way, during stops at roadside inns and the like, those not with the caravan could have been met.
Talashia intends to use Sandpoint as a 'base' of sorts, while she hunts for relics and writings in the ruins of old Thassilon.