My "advice" is to wait a couple MORE weeks and then casually ask him how it is going.
But what *I* personally would do? Have a MAJOR discussion ASAP about why he is procrastinating on this and whether it is a sign that he doesn't want to get married, ending with some kind of resolution...either him setting the exact date he's getting this all taken care of, or a breakup. That is because I am very extreme and dramatic and perhaps high-maintenance. If something's bothering me (especially with my SO) I have to get it out in the open.
I don't think what I would do is the "right" answer at all but just being totally honest.