There is a phrase exactly for this situation: blank canvas paralysis.
It is a fairly new coinage and it is originated in painting where painters can't start painting and keep staring at the blank canvas; but it can be applied to any situation.
Whenever you are about to start something new, you risk ‘Blank Canvas Paralysis’, the inability to get started. It is frightening, frustrating and causes you to doubt yourself, but once recognized for what it is, it loses some of its power and you can find ways to deal with it.
However, it is not only painters who face the blank canvas. Everyone eventually faces its petrifying stare.
In a letter to his brother Theo, Van Gogh wrote:
Just slap anything on when you see a blank canvas staring you in the face like some imbecile. You don't know how paralyzing that is, that stare of a blank canvas is, which says to the painter, You can't do a thing. The canvas has an idiotic stare and mesmerises some painters so much that they turn into idiots themselves. Many painters are afraid in front of the blank canvas, but the blank canvas is afraid of the real, passionate painter who dares and who has broken the spell of `you can't' once and for all.
Source: Vincent van Gogh. Letter to Theo van Gogh. Written October 1884 in Nuenen. Translated by Mrs. Johanna van Gogh-Bonger, edited by Robert Harrison, number 378. URL: http://webexhibits.org/vangogh/letter/14/378.htm.
