You dont FILE for independence~ You Declare it. Kenya Declared Independence on December 12th, 1963 when they ratified their Constitution (Check the first 350 posts, you missed the discussion this morning). The Republic was ratified in 1964 but they operated as such until it was ratified.
Sometimes colonies have been decreed free by the colonizer (read evil imperialist), so that it is known that on a certain date the independence would be official.