usually a company is delisted long before bankruptcy. one that goes from listed company (i.e. not pink sheets etc) to bankruptcy usually will make front page headlines. It is a big deal if bankruptcy has not been telegraphed.
if you are trading those kinds of equities, and have never worked in distressed assets, in a workout group at a bank, or have any experience in the space, then i should give you a warning about how in the dark you are. It is a confluence of legal discussions, cash flow forecasts, who controls the company (the creditors / banks if there is debt where interest can't be covered) union negotiations etc.
Although i was neither a distressed trader nor pure corporate advisory, i have advised companies on this before, and i have been part of creditor groups on several occasions that have negotiated distressed deals into bankruptcy. A lot of competing interests and heated discussions. You have so many moving parts - taxes, unions, can you find the right team to do something with it, or are there any in the industry you could lure? Could you line up independent financing for a financial buyer if no strategics will bite? Are you willing to indemnify for certain liabilities...too many to list. When do you decide to just throw in the towel?
Rarely do you just decide "overnight" and you will have made representations as a going concern in your financial statements.