Webinar

@Garry You can edit a webinar via your Zoom web portal. 

Login to your account at zoom.us/signin and then navigate via the panel on the left to "Webinars". 

I recommend in the future utilizing our practice session feature so that there isn't scheduled "dead time" before the meeting. Panelists and Hosts can join when needed before the meeting to practice the presentation. When complete, the Host can hit "Start Broadcast". 

Webinars can be started anytime before the start date and with practice session being utilized, there will be no worry of automatic recordings starting or risk of attendees joining. 

Practice Session: https://support.zoom.us/hc/en-us/articles/206316975-Webinar-practice-session