(a) The department shall provide to a fire fighter or police officer notice of the time and location of a meeting or hearing not later than the 48th hour before the hour on which the meeting or hearing is held if the meeting or hearing is:
(1) related to an internal departmental or other municipal investigation of the fire fighter or police officer at which the fire fighter or police officer is required or entitled to be present, including an interrogation;
(2) related to a grievance filed by the fire fighter or police officer under Sections 143.127 through 143.134; or
(3) an opportunity to respond to charges against the fire fighter or police officer before the department terminates the fire fighter's or police officer's employment.
(b) A fire fighter or police officer may waive the notice prescribed by this section.