Sending Analog Input Data from Serial Port to Google Sheets
Use Google's time stamp format: MM-dd-yyyy hh:mm:ss, see Google Sheets API v4 - Date and Number Formats.
There are a few ways. For example:


A PC connected to the Internet with software on it that listens for data form the Arduino. It would get the Arduino data over serial then send that via the Internet to Google.
A Wi-Fi, or network, shield connected to the Internet. You could then use Google's API to send the data directly from the Arduino, see Google Sheets API v4 - Writing.
Or - as you mentioned - physically get the SD card and manually upload.