Когда хата сгорит, сажи не трусят

See После драки кулаками не машут (П)

Cf: It is too late to cast anchor when the ship's on the rocks (Br.). It is too late to cover the well when the child is drowned (Am.). It is too late to lock the stable door when the steed is stolen (Am., Br.). It is too late to throw water on the cinders when the house is burned down (Am.). When the calf is drowned, we cover the well (Br.). When the house is burned down you bring water (Br.)