Here is an idea:

I would like to have a notification when then travel time of my commute is less that 30 minutes.
So I would set a time-window from say 630 pm to 730 pm and the app would notify me when the travel time to my desired destination is under 30 minutes.

This would be a great feature to have. And yes, this idea is free and clear for waze to use!

Regards,

Clueless2010