Appointment added without my acceptance

Appointments and dates are added to my calendar from meeting request of other users before I accept or decline them. My admin assistant who has editor permissions to my calendar is the only person besides me that should be able to add appointments. Is there a setting somewhere that will stop meeting request from being added to my calendar unless I accept or decline the request. I am not always able to accept or decline right away and, I do not want any adjustments to my calendar until I can respond! If I do not respond, I want no action taken.