{v. phr.} To do something at the right time; not wait too long. * /Dick had a free hour so he made hay while the sun shone and got his lesson for the next day./ Compare: MAKE THE MOST OF.
MAKE HAY WHILE THE SUN SHINES
Meaning of MAKE HAY WHILE THE SUN SHINES in English
Slang English vocab. Английский сленговый словарь. 2012