If event starts on Google Calendar then send SMS to number in description of the event
If
Any event starts
This Trigger fires a set number of minutes before the starting time of any event on your Google Calendar. Note: The time in the ingredient will be based on the timezone set in Google Calendar.
Then
Send an SMS
This Action will send an SMS from your Android device to any phone number you specify.
ID F5UTf4qa
Explore more great ways to automate Android SMS and Google Calendar