There is an old saying "well begun is half done"-'tis a bad one. I would use instead-Not begun at all 'til half done.
John KeatsThe genius of poetry must work out its own salvation in a man; it cannot be matured by law and precept, but by sensation and watchfulness in itself. That which is creative must create itself - In Endymion, I leaped headlong into the sea, and thereby have become better acquainted with the soundings, the quicksands, and the rocks, than if I had stayed upon the green shore, and piped a silly pipe, and took tea and comfortable sdvice.
John Keats