You do NOT need a lawyer to handle a simple sponsorship agreement. There's plenty of templates out there to use for your contract that are binding and effective. Google em.

The easiest way to handle it is to get your funds in January or whenever your agreement begins and then you don't have to worry. A wrap isn't going to last two years anyway so if they bail then re-wrap.

And here's the reality, if you're worried about non payment in the early stages then chances are you may not be dealing with the right partner.