We recommend mentioning or even showing your room during your first call.
Explain to the customer that:
"This room will enable us to keep things organized, share content and next steps" .
For more tech savvy customers explain that this room will enable you and your customer to mutually collaborate and show them how to tag and comment.
We recommend you initially share a lean room with:
a welcome message
onboarding process overview
onboarding deck
integral documents / presentations to the beginning of the onboarding process
You can add more sections as the onboarding and customer life cycle evolves.