A weather forecaster told us this morning that sunrise delayed the most at 6 : 51 on January 13th, birthday of Mei-Shun. Sunset got the earliest at 16 : 28 on December 12th last year, he said. The shortest daytime comes on 冬至=toji, the 4th of winter 二十四節気 on December 21st; seems to include both of above, yet actually does not. Longer days makes it easier to start anyway.