oct 13, 1156 - Merlin creates Camelot
With the creation of the round table, Merlin created a city for Arthur and everyone else. After this period Merlin fades away from Arthur since he is grown up. Different stories have told where Merlin ended up but no one knows for sure. we just kno that after this point he goes away from Arthur;s life.
Added to timeline:
King Arthur's lifetime