When did wilfred Owen start writing poems?

Although Wilfred Owen is best remembered as a poet of WW1, he had poetical aspirations long before the war. There is evidence he was writing poetry early in his life.
In a letter to his mother while still a student he wrote:

I felt my boyhood fill
With uncontainable movements; there was born
My poethood.

There is no firm date on when he started writing poetry. However, the bulk of the work he is best known for was written in 1917 and 1918. It was then that he really felt he had become a poet:

I go out of this year a poet, my dear mother, as which I did not enter it. I am held peer by the Georgians; I am a poet's poet. I am started.
_{letter to his mother, Dec. 1917}

Oxford University has a digital archive of his original hand written poems. Type in Wilfred Owen in the search menu when you get there and the papers will be viewable.