Use the adjective opportune to describe especially good timing. A snowstorm is an opportune time to make extra money shoveling your neighbor's driveway.
You can see the word opportunity in opportune. Both words come from the Latin word opportunus, meaning "favorable," which itself is derived from a phrase that describes wind blowing toward a port. Just as the wind helps speed ships toward shore, something that is opportune offers favorable circumstances for accomplishing something or doing something.