Urgent!!! Question regarding editing Petitioner Start date in US VISA scheduling appointment

Hi all, I may have changed the petitioner start date and booked a H1B dropbox appointment. But, I wanted to change that as per my new approval document. Would, Not reflecting the actual start date in visa appointment; cause any issues? Can I change it at the dropbox location, Chennai! While at the appointment?

Or How do I edit it now without having to schedule a new appointment?

I am unable to verify either; in visa scheduling website, what was submitted as the start date!!? How do I verify it?

Has anyone gone through similar situation? Do I have to worry about it at all? Please advise.

Thanks.