Change time zone timestamp

The timestamp applied by Google is based on the server within Google that actually processes the form submission. I don’t know of anyway to control that as it isn’t a field that is part of the form itself.

However, what you could define another field which is somewhat of a duplicate of the Google defined column to capture the timestamp. Set it up as a “hidden” field within the Google Forms plugin and define it as a “timestamp”. The plugin will set the field based on the time and date or your WordPress installation when the form is submitted.