When does user can signup as attendee?

This could be an awesome Webinar plugin for me!
I use Youtube live for the webinar, and it should do the work for me.

I setup the webinar to be four days from now. It’s on countdown state, but when does User able to register? I test and try the date to be current time, and I can see attendee signup page. Can we set it up to let attendee able to signup anytime?

Thanks!