It's below the recommended temperature, but that's usually more of a concern later in the year. When it's cold, a plant's metabolism slows, so it can take longer to work. In Spring, as the temperature increases, it should work fine, but it might take longer than advertised.
I googled weather for Madison, and it looks like you're due some rain followed by some warmer weather and sunshine. Personally I would wait a week if it's possible. Spraying tomorrow won't really make it go much faster.