The shipper may be talking about the load he has and even tell you what he is paying; that's good but before you even think about looking for a truck, you will tell the shipper that you will need to get set up with them. They should know what you mean; if not, tell them you have a package of information, including your broker authority, etc. But you don't need a broker-shipper contract, necessarily.
Then you will ask the shipper how quickly they normally pay freight brokers. He should be able to tell you and it had better be at least within 30 days.
Lastly, you get the shipper's full name and their address and then run a credit check. This is mandatory unless you want to be working in the dark as far as your cash flow is concerned.
So, yes, it's good to find a shipper who is anxious to work with you; but you have to do first-things-first and get started on the right foot.
In short, don't jump out there searching for a truck before you haven't been properly set up with the shipper including a credit report.