APPT limit minimum (as well as maximum)

A quick question, I have searched the forums and haven't been able to find anything related to this yet.

I would like to set an appointment minimum, as well as a maximum limit for people to create appts in.

IE, at present here it is Saturday morning, I don't have any appts with clients this morning - or so I thought, when I find that someone has booked overnight and I find out 10 minutes before the newly booked appt!!!!!

Being able to set a minimum duration in either hours or days would be a very handy feature. Hopefully there is a sneaky way to do this (@hakan ???) otherwise perhaps this post can be moved to the requested features section, where it would be very welcome in an update.