Source, in full
This expression greatly predates any use of it by Edison. George Head used it in A Home Tour Through the Manufacturing Districts of England in the Summer of 1835 (1836), p. 198, in which he states: If time be judiciously employed, there is time for everything.
Notes from Wikiquote
There is also an entry in the Bible (Ecclesiastes 3:1) that says There is [a] time for everything, however this varies a lot between the different translations.