I am in the process of a 3-5 year project of doing this very thing at our museum which houses over 500,000 artifacts, many of them painstakingly small! I agree with working on the accessioned artifacts first because their information is more readily available by computer. We have several interns and one volunteer who (when available) work with me going through boxes of artifacts just checking to see if each item was photographed, and whether they are in the documented home location. This saves me a lot of time to work on the ones that either have no accession number at all, or some other issue. Once a box is complete I create a report of all the items in that box, and then if an item is added at a later time, it is easy to update. I know it is going to be a slow process, but the goal is achievable… one day at a time!