For holiday rental apps such as Airbnb, booking.com and likes. What is the best time/stage to ask Hosts/listers for phone verification? On signup or after they list the property? Keep in mind, they have to verify before the property is published!
I would force it on listing and soft-suggest on registering, that way, verification isn't a blocker to registration and there's value in the user going through the process on listing to secure a service.