“But when will I do the starry sky, then, that painting that’s always on my mind? Alas … the most beautiful paintings are those one dreams of while smoking a pipe in one’s bed, but which one doesn’t make. But it’s a matter of attacking them nevertheless, however incompetent one may feel vis-à-vis the ineffable perfections of nature’s glorious splendours.”
— Vincent van Gogh, letter to Emile Bernard, June 1888.
There isn’t the perfect time, the right time, the time that guarantees success in a painting; waiting for it is procrastination. You may not succeed, it may be beyond you at the moment, but anticipating it to be and thus not trying means you’ve definitely failed, through inaction. Trying and failing gives you something to work with in finding your way to getting there another day. Plus there’s always the possibility it’ll be one of those days where you make a leap in your painting and things flow and work.
When you think of Van Gogh’s “Starry Night” painting, I bet you don’t visualise the Starry Night in the Musée d’Orsay in Paris, but rather Starry Night in MoMa in New York, which painted months later.