no time like the present

(There is) no time like the present. (=Do what you are supposed to do right away. Do or say it now.)

≈ Cейчас самое подходящее время;
≈ Лови момент, не упускай момента;
Лучше всего сделать это прямо сейчас.

Example 1: Go ahead and call him—there's no time like the present. (The American Heritage Dictionary of Idioms)

Example 2: "When should we start cleaning up the house?" "No time like the present. "

Example 3: Start studying for the big exam now, instead of waiting till the night before. There's no time like the present. (McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.)

Example 4: "When do you think I should phone Mr Hughes about that job?" "Well, there's no time like the present." (CID)

Related vocabulary:
[never put off until tomorrow what you can do today]

This adage was first recorded in 1562. One compiler of proverbs, John Trusler, amplified it: "No time like the present, a thousand unforeseen circumstances may interrupt you at a future time" (The American Heritage Dictionary of Idioms).