How long does it take for a loan company to repossess a vehicle?

We are in the middle of paying our lawyer off as we have him in a retainer basis. We are able to skip the month of May for car payment so the next month payment we will skip will be June. How long after that may they repossess our vehicle? We are trying to just get to October when we will have a few thousand coming to us to put down on a different vehicle. Can I just pay them a little here and there to keep them off our backs?