It seems that proof sheet continuity is more important than a good filing system.
Wait untill you have over 30 thousand negatives. Then you may find that the Print File System approach to filing and proofing isn't such a good way after all.
Set up a good database.
Catalog by topic.
File by topic.
One negative and it's proof per envelope.
Individual envelopes from Archival Methods...
Use a card file type cabinet.
File by topic. (I already said that)
The sooner you start, the less formidable the project.
After 35 years, I can go to any negative in a few seconds regardless of negative size or when it was shot.
More details? P.M. me