On a certain month of a certain year, he saw a piece of news in the newspaper.
On a certain month of a certain year, he began to have a long dream.
In a certain year and month, he was still a brilliant guitarist on stage, and he was also a secret admirer watching him silently from the audience.
In a certain month and year, his wings had not been broken.
In a certain year and month, they missed it before they even started.