I agree, although it is important to have at least some plan on how to handle a sudden wave of new users. There is usually little-to-no-warning for when a place will get attention: maybe some journalist decides to mention this place, or reddit.com does another major oopsie. The Lemmy ecosystem was overall ill-prepared for the sudden massive influx, and I'd hate to repeat history.

A few things to think about (from my experiences elsewhere):

• Server backups
• How many users are too much for the current staff to handle? Are there any users you can deputize in an emergency, or even better, prior to an emergency? How will you onboard them so they act appropriately, and are you fine kicking staff who can't behave?
• What technical measures can you take to ease the load? Auto-moderation bots? Limiting maximum signups per day? Can you set any up in advance?
• [It seems you already know this one] Which is more important: more users or good quality users? Will you take a hard stance on bad behaviours before they can become normalised?