You’ll find some relevant information about this in this forum thread, where we also discussed the talk by Bhante Dhammavuddho:
There, with some more references, Lal explained that the phala citta followed right after the magga citta; thus one becomes a sotapanna in one moment (citta vithi).
When one becomes a sotapanna anugami, at the Gotrabu stage, one is on the path to become a sotapanna, but that can take some time.
Also, the following post is about the four conditions for the sotapanna stage:
… and yes, listening to Dhamma talks is one of them.