A contractor is filing bankruptcy. Should I sue now or wait?

I'm unfamiliar with bankruptcy laws so I'm wondering if a contractor owes me money and plan to file bankruptcy, if I don't sue before they file, will I still be able to sue later on. I don't want to precipitate any action but I also know that they are trying to do the right thing. Unfortunately, there's a lot of money at stake and I don't want to lose out more than what I have to. Any advice? This is for an unfinished/late contract.