Hours are Central, 24-hour. A slot has to fit entirely inside the window and clear every appointment by the buffer on both sides. Anything marked free on the calendar doesn't block; tentative does.
Open times
Offer them by email
Lands in Outlook as an unsent draft. Nothing goes out until you press send.
Hold one on the calendar
Select exactly one time above. Teams meetings get a join link minted by Microsoft and written into the event. Either way the event goes on your calendar with no attendees — Graph mails invitations the moment an event has an attendee list, and nothing in REGgie sends. Add people in Outlook and press send yourself.