Invite 100+ guests to Google Calendar event

I need to invite 250 emails to a Google Calendar event. I was able to add the first 100 without any hassle. But any invite after that would give me an error, "Oops, we couldn't update this event. Please try again in a few minutes".

After hours of trial and error, I discovered that I can invite one guest to my event every 30 minutes. This is extremely time consuming and inefficient.

How can I resolve this issue and invite ~250 guests at one time?

Add the event participants to a Google group

• You can invite up to 200 guests to a Google Calendar Event
• However, a Google Group counts as one guest
• A Google Group can have up to 2000 members
• If you add multiple participants to the same group and invite to your event the group instead of the single participants - you can reduce the number of guests below the allowed limit.

References:

• Guest limit for invitations
• Google Groups Membership