The later it gets the greater the likelihood of failure. If you are asking generically as a means to gaining some business, the earlier the better. If you have a specific client in mind, I would start by discussing the option with them; explain it may already be too late but that you'll try. Obtain an authorization to speak to their lender and then see where you go from there. If the lender says, "bring us an offer" get busy, list the property and hope for the best. If they shut you down, you may still try but you'd better have an offer right away at a compelling price to get their attention.
Some of this depends on how hard and fast you are willing to work, how determined you are, how experienced you are in negotiating with lenders and of course which lender is involved and if you an reach someone. I hope this helps.