Launching Appraisd to your staff will be one of the easiest software / system implementations you've done. Once you've been through the implementation checklist, you're ready to go. 'Launch' in Appraisd simply means your staff receiving an email containing their login instructions.
Instead of launching to everyone at the same time, you can launch Appraisd to individuals on an ad-hoc basis. Simply send them a password reset link from their profile page. See Password reset / Cannot log in.
Most common is a mail merge launch where you or your Appraisd account manager will email all your staff with their login details. The email typically looks like this. See Mail merge and Welcome Email.
After launch, your account manager will monitor usage by your staff and ensure things go smoothly, liaising with you if necessary.