When. Morning and evening as part of the daily portion, and at any point where one of the eight is actually pressing. It is the long form; a shorter version naming only the first four is also widely said.
The words. Eight things, arranged in four pairs, and every pair is two sides of one problem. Hamm and hazan: worry looks forward at what has not happened, grief looks back at what has. Between them they cover the whole of what a mind does with time. Ajz and kasal: inability and laziness — one cannot, the other will not, and from the outside they produce the identical empty afternoon. Bukhl and jubn: miserliness withholds your money, cowardice withholds your self; both are a refusal to spend what you have. Then dala' ad-dayn and ghalabat ar-rijal.
Two phrases worth unpacking. Dala' is a bending or crookedness in the ribs — debt is described as a weight that bends the frame, not as a number. And ghalabat ar-rijal is 'the overpowering of men': being under the hand of people who can compel you. It is placed immediately after debt because that is exactly where debt leads.
Why refuge and not relief. Every clause is a'udhu bika, seeking refuge, rather than a request to be rescued. The supplication is preventive. It is said by people whose affairs are fine, which is when the eight are easiest to say and hardest to feel.
A note. Saying it is not an alternative to repaying what you owe; the last pair in particular reads as a description of what to avoid arriving at.