I think my youngest was 2.5/nearly 3 when we did our first Disney cruise. We had a blast (including our handful of kids). But we didn’t use the kids club on that cruise or any subsequent cruise (on Disney or other lines).
Here’s the thing: the clubs are basically daycare for young kids. You are rolling the dice of your kid picking up germs in that environment. Older kids (tweens/teens) who are extroverted joiners tend to enjoy going to the club, making friends, and then wandering around in groups outside of the club.
Anyway, our kids loved the Disney cruises we did when they were younger.