It is unknown how old Morgana was when she first started to occupy these chambers, although she presumably came to Camelot at Gorlois' death, which occurred when she was ten years old. If, however, she had for some reason been born in Camelot then she may well have occupied the rooms from birth until her eventual leaving of Camelot.
When Merlin found Mordred, a young Druid boy, on the run in Camelot, he brought him to Morgana's chambers. Morgana surprised, hid Mordred behind the screen in her room when the guards came to search for him, then answered the door. She informed the guards she had not seen the boy. She then tended to Mordred, who had been injured beforehand, as the wound became infected his condition worsened. When Arthur came to her chambers to look again for the boy, she tricked him into not searching her rooms properly by telling him to look behind the screen, which was where Mordred actually was, which Arthur took to be her mocking him. Mordred left her chambers when she and Arthur smuggled him back to his people.
When Morgana turned on Camelot and left the citadel, her rooms presumably remained vacant.