You've managed to put together an event. You even have experts coming in. Good job, congrats. It’s now online event promotion time.
If you want your experts to promote your event, stay out of their way.
There’s no specific date or time to stop registering people to your event. You can keep on getting last minute subscribers right up to the last five minutes before your launch. Some techniques you can use include:
Social media pages
Carousels
Message your mailing list