@Scendre this is a limitation of Zapier in that it only processes data moving forward, however we can "fool" zapier to trigger on other data... In your case since it's a one time "import" this is the easiest method I would recommend:
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Note: After writing up the description below I realized your goal was to just get this data into a google sheet, running it through Zapier is unneeded as you'd need to export the data from wordpress (try this plugin) and that would provide you with a CSV of the data, just open that file in Google Sheets and remove the columns/rows you don't want and then if you need to copy the data from the remaining 4 columns and past it into your desired Google Sheet. If, however, you need to run these 4 data points through Zapier to process/format them etc then you can follow the instructions below.
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First export your data from Wordpress and remove everything except the 4 columns you want:
- Published date
- Title
- Excerpt
- Url post
Second create a Google Sheets file with those 4 column names (in the same order as the exported data you have).
Third copy your existing zap and change the trigger to Google Sheets -> New row in Sheet point to the sheet you created in the second step above. Then map the four data points (the four columns) to however you use it in the rest of the zap.
Fourth, copy a row from the exported data to the sheet you created in step 2 above. To test it... if the zap fires and ran the way you wanted to, copy up to 100 rows at a time and paste them into the second spreadsheet.
(If you do more than 100 in ~3 minutes Zapier will hold the tasks as a task flood protection. While doing something similar recently, I knowingly flooded Zapier with 1000 rows, and then logged into Zapier and told it to play all 1000 tasks... after a few minutes it finished everything fine. )
