I’ve had success with the Date/Time Selector minimum and maximum dates, but I’m hoping someone has a creative idea about how exclude certain days of the week… preventing someone from selecting any Wednesdays in the selector, for example. Thoughts?
Thank you SOO much!
8 years later 
Good question! I don’t think this is possible natively, but you can use conditional logic and do an action when the user selects a date that is a Wednesday:
This Date/TimePicker's value formatted as Friday is Wednesday (where the "formatted as Friday" part is "custom format" in "dddd" format)
It’s not entirely what you were looking for, but it’s something 