Making Event Registration private

I'm not finding any documentation on how to use the "Access" and "Registration Access" options.

I would like to have an event registration available only to a group of invitees for a short period of time, then open it up to the public. What are my options for making this happen?

Or, How can I create an event, not publish it visibly on my site, but have a live registration URL to distribute? Thanks!

I think I would do it one of 2 ways on my site:

When you're editing an event, you should see the following on the right-hand column:

1) You can change Access and Registration Access to the specific Joomla user group that you want to see/register for the event (and change back to public afterwards to open public registration). This "access level" is assigned to users in the Joomla user manager.
2) Alternately, you can enter a Password in the Event Password box and send that password out to your chosen members. Remove the password after to open registration to the public.