Yes it takes time to populate the relay. You should add relays to your firehose to start collecting events as they happen, or like Veritas said you can manually sync to do it faster.
To configure your firehose go to: Dashboard -> Relays
On ditto we just have 2 added, and it's pretty sufficient:
wss://relay.damus.io/
wss://relay.primal.net/
The sooner in history you start your server and your firehose, the more events it will have. Right now, you have practically zero so every single new person that joins is a person your database does not know about. So, yeah, each person may need to be manually synced if you don't want to wait.
However, if you just sit around and run your relay and collect events for a while, eventually you'll get events that include info from all across Nostr - including your potential users you want to join as long (as you set up your firehose).
On Ditto.pub and Henhouse, for example, I never have to do this manual syncing because we've been running this database for long enough we have a lot of Nostr events in here. However, occasionally we still find people who are new to us and just trust those events will eventually turn up as needed.
And I think you also asked somewhere in this thread "Why do users add relays?" The answer to that is that when a user adds a relay their events are published to that relay. This does not change the relays that Ditto reads from, only the firehose (under the dashboard) does this.
The reason for this is a bit in the weeds, but it's related to the way Ditto is inherently different from other Nostr clients by being community-oriented. On a regular Nostr client each individual user is responsible for curating their own experience (with all the risks that come with that). However, on Ditto, you as the admin are responsible for leading the whole community - including populating the database securely.
I know it's a lot of info, but hope this helps!!
