How soon after a car is paid off can i seize this girls car?

I have a girl who I have judgment against, I would garnish her wages, but someone else is. I know that she has a car, but it is financed. She has year and half of it. Would there be a way I can seize it the second she pays it off? Like be waiting at place she finances through when she makes her last payment. Could I take it the next day? How long would I have to wait?