Translation of intranslatable is my favorite sport :).
Here's the corresponding proverbs translated from Serbian:

>"A stitch in time save nine."
"Who's early grabs two lucks"
>"Never put off what you can do today until tomorrow."
"What you can do today, don't leave for tomorrow"
>"The early bird gets the worm."
"Who sooner to the girl, his the girl"
>"Alway let sleeping dogs lie."
There are two for this: "Don't poke the [lady]bear" and "Don't touch the lion while he sleeps". Both actually rhyme in Serbian.
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>"Always make a point of going to other people's funerals, otherwise they may not come to yours."

"Sterility is hereditary: if your parents had no children, most likely you won't have any either".