This is an issue that frequently frustrates donors, but that is often because it's hard for people outside museums to appreciate the glacial pace that things often move at. Museums are now (in general) very understaffed and under-funded, and an enormous amount of paperwork goes on that you don't see. Maintaining a collection is a major work, and the displays are the fun bits that the curators would love to do more of, if only they had time.
In this case, it sounds like it involves creating a whole new display. Before that can happen, all the specimens need to be properly databased, and the existing displays need to be modified to accommodate the new material, or cases shifted around. Research needs to be done in order to put together informative captions (the curators will know less about the fossils than you do, in most cases - hardly anywhere outside the national museums have specialist geological curators nowadays). The captions sometimes then have to go through other departments for readability etc., and be formatted correctly, and this alone can add weeks to the process in some museums. New cases may have to be bought, and that involves applying for grants first (which may or may not be awarded). What I'm trying to get across is that having an entirely new display put together by next year is actually very good going.
I've got a suggestion, which you may well decide to ignore... but anyway. Offer to help in putting the exhibition together, in cataloguing the finds and writing the captions. If you can give them some time as a volunteer, you'll help to push the process along, as well as getting the satisfaction of being really involved in the process and the finished product. Also, once you get to know the staff and the struggles they have to keep the place running, you might be more appreciative of the timescales involved in getting the displays right.
It's a wonderful hobby, and you can really make an impression in the field simply by finding things and making them available for other people to see. Good luck!
p.s. I've been a museum curator and an academic researcher, and am now largely an amateur (working a lot with our local, very small museum), so I've seen all sides of it over the years...