Should I put a charge on a property to get paid?

Hi everyone, I’m a builder, and the owners of a property I’m working on agreed to let me put a charge on their property to make sure I get paid. The thing is, one of them already has a charging order on it, and that person could force the property to be sold. They have to sell by June 2015 anyway, so I’m wondering if putting a charge on the property is worth it. Will I definitely get paid before the other charging order holder? Also, how long does it take to put a charge on a property?