After signing up for a ListenBrainz account and importing my Last.fm history, all of the charts on the "Reports" and "Charts" tabs said "Statistics for the user have not been calculated". It would be helpful to tell users when they should expect the statistics to be generated. A simple note saying that they should expect it to be generated every 24 hours would probably be sufficient.

There are multiple places in th UI where that message needs to be changed:
https://github.com/metabrainz/listenbrainz-server/search?l=TSX&q=Statistics+for+the+user+have+not+been+calculated