This site is currently struggling to handle the amount of new users. I have already upgraded the server, but it will go down regardless if half of Reddit tries to join.
However Lemmy is federated software, meaning you can interact seamlessly with communities on other instances like beehaw.org or lemmy.one. The documentation explains in more detail how this works. Use the instance list to find one where you can register. Then use the Community Browser to find interesting communities. Paste the community url into the search field to follow it.
You can help other Reddit refugees by inviting them to the same Lemmy instance where you joined. This way we can spread the load across many different servers. And users with similar interests will end up together on the same instances. Others on the same instance can also automatically see posts from all the communities that you follow.
Edit: If you moderate a large subreddit, do not link your users directly to lemmy.ml in your announcements. That way the server will only go down sooner.
Saldy it's very common to have this influx towards the "main server" as people that are not used to the federated aspect come to the platform.
Either way, it would be interesting to collect this information and later post some metrics about the exodus from Reddit, kind of like how Fosstodon and other Mastodon instances did when Twitter had their issues.
I don't think you can expect the bulk of reddit (not technical) user base to care or know what federation is.
If people need to hunt out servers they will stay on something centralized until an alternative takes over.
Hence why Mastedon is dead in the water.