Many organizations launch when the platform is ready, not when the community is ready.
Some pick an arbitrary date and stick to it.
The result is a lot of empty launches.
You're not ready until you've properly seeded the community. You're not ready until you have a group of 50 to 100 people interacting and using the platform.
You're not ready until you know how to engage members and keep them participating over a sustained period of time.
You're not ready until your boss understands the community, it's benefits and has reasonable expectations.
You're not ready until you've got the access and support of your company to get employees involved and interacting in the platform.
But if you've got all this, then you don't need to launch. You just need to grow.