I don’t think google pushes original date and time for an udpated event. But here is a work around you can try.

Google calendar sends a unique eid with every request, you can find it in html link field, this doesn’t change even if event is updated. Setup a zap to write it some where like SQL along with original event date and time. Retrieve these details back in the Zap when event is updated. 

Hey there @Drex! Thanks for reaching out in the community! I did some digging and wanted to confirm what @subhash mentioned in that original date/time isn’t sent to Zapier for an updated event in Google Calendar. 

The created time of the event is sent but I’m not sure if that’s exactly what you needed.

@subhash also mentioned keeping a table of the event ID’s every time an event is created with the original start times and referencing those ID’s when it’s changed.
This would be a lookup table and I wanted to share some resources on that if you decided to go that route. 

I hope some of this helps!