Delays are dangerous

Cf. [c 1300 Havelok (1915) l. 1352] Dwelling haueth ofte scathe [harm] wrouht.

Delayes breed daungers, nothing so perillous as procrastination.
[1578 Lyly Euphues I. 212]

Shall we go presently [immediately], delaies are dangerous.
[1655 J. Shirley Gentlemen of Venice v. 62]

I have always found on all subjects that ‘delays are dangerous’. ‥It is expedient that we marry young.
[1824 J. Fairfield Letters (1922) p. xxxi.]

What a pity Master Hector left it too late. ‥Delays are proverbially dangerous.
[1930 B. Flynn Murder en Route xxxiii.]

Related to: action and inaction; procrastination

Bibliography of major proverb collections and works cited from modern editions is available here.