http://wmj5kiic7b6kjplpbvwadnht2nh2qnkbnqtcv3dyvpqtz7ssbssftxid.onion/help/administration/reference_architectures/index.md
For example, if you have 3,000 users but also know that there's automation at play that would significantly increase the concurrent load, then you could start with a 100 RPS / 5k User class environment, monitor it, and if the metrics support it, scale down all components at once or one by one.