Prompt User to Set Custom URL during Event Creation

[snackman]

Is your feature request related to a problem? Please describe.
When I create an event I can't change the URL afterward, it would be good to know beforehand.

Describe the solution you'd like
Let me know what the URL is going to be, based on my event title, and give me an option to change it

Describe alternatives you've considered
It would be even better to be able to change the URL after the event's created, but I understand that build would entail more scope.

Additional context