i would say there is no cutoff. if you think it's time to manage your
collection just do it. there are a bunch of
software applications on the market that
help you do this from the free to the big bucks, from simple solutions (an excel spreadsheet) to fully dedicated databases. the earlier you start the easier it is to get a hold of what you spent, when, from whom, etc.
i would invite you to try
http://www.tantaluscoins.com/index.php which allows you to start cataloguing your
collection within a couple of minutes. as the project lead i'm committed to making it the most sophisticated ancient coin
software available regardless of which
area(s) you specialize in.
ras