Friend owes husband money

My husband is a contractor and did his friends kitchen. He finished in May. His friend still owes him a lot of money. The friend is getting the remaining money from his step dad (who is rich) cause he doesn't have the money. The stepdad knew he had to pay money towards this remodel but the friend added things on which made the bill go up. So my husband asks his friend every week what's going on and he keeps saying "mid week" or "by the end of the week". still nothing. We have a signed contract and I am wondering how long we wait until we get a lawyer involved. And do we say pay now or a lawyer will be contacting you. Or do we not tell him a lawyer is going to get involved?