YOu can add indexes on the fly. You would need to issue a CREATE INDEX SQL statement or use the Create Index Btrieve API call.
As far as waiting until everyone is off, it might be a faster if you do that because the index B+ Tree will be created when the index is added and if users are working with the data, that B+ Tree will take longer to create.
info@mirtheil.com
Custom VB and Btrieve development.
Certified Pervasive Developer
Certified Pervasive Technician