Typically, attendees will only be able to enter the event 30 minutes before the start of your event. The Enter Event button will only appear on your event page 30 minutes before the event. If you want your attendees to be able to enter earlier, you can adjust the Pre-Event Access start time to an earlier time so that the Enter Event button would appear earlier.
From your admin console:
Go to Event Details
Scroll down to Pre-Event Access Starts
Enter your preferred date and time as to when the Enter Event button will appear on your page that will give you attendees access to the virtual event hub
For Free, Starter, and Scale Plans, you can set the access up to 24 hours early.
For Professional and Enterprise Plans, you can set the access up to 168 hours early.