The earliest known inscriptions in the Burmese script date from the 11th century. It is also used to write Pali, the sacred language of Theravada Buddhism, as well as several ethnic minority languages, including Shan, several Karen dialects, and Kayah (Karenni), with the addition of specialised characters and diacritics for each language.
From when are the  first impressions of the visually displayed language ?
The earliest known inscriptions in the Burmese script date from the 11th century.