I would strongly advise against installing it yourself. It is not nearly as easy as it looks. The wrap business is so competitive that the install should not be a big factor.
Make sure you are getting the correct grade of vinyl wrap material as they vary widely in longevity and price. Even if your supplier drop names like 3M and Avery please realize that both these companies make many grades of vinyl. Some are designed to be on for short duration and some are designed semi-permanent use that are strip-able when the vehicle is sold or wrapped again.
If the van was just painted make sure the paint is well cured before you wrap it.