I am relatively new in my implementation of GTD too, and have also run into this problem. I have a modified "ticker" file that is a small plastic standing desktop file that looks like this: http://www.amazon.com/Oxford-Decofle.../dp/B0012VIJGS. The hanging folders I have are "Now", "Soon", "Month", "Later", "Waiting", "Errand"

In your example, I would put a binder clip on the materials, with a dated Post-It on the first page that listed the Next Step details. Then, I would file that packet in "Today" if I had to do them today, or "Soon" if it can wait, or "Month" if I should look at it again in a month. If I have stuff I am waiting for that is time sensitive, rather than put it in "Waiting", I put it in the appropriate time-frame for when I will want to follow-up if I need an answer back.

In the GTD book, the tickler file David Allen suggests had a tickler file for every day of the year. I found that too cumbersome, because if I needed to retrieve something, I had a hard time finding it. This modified "tickler" limits the places an item may be located.