Google Ads Editor provides three ways to update start dates and end dates for campaigns and sitelinks: CSV import, the Make multiple changes tool, and manual edits on the Campaigns tab or the Sitelinks tab.
For CSV import and the Make multiple changes tool, always use the format YYYY-MM-DD.
For manual entries on the Campaigns tab or the Sitelinks tab, use the date format specified by your computer's operating system. Google Ads Editor displays your OS date format beside the "Start date" and "End date" field labels. As a shortcut, you can also click the calendar icons to select a date.
For manual entries (not CSV import or add/update multiple), you can vary the date format slightly, as long as the year, month, and day units are in the same order as your OS date format. For example, suppose your OS uses the format M/D/Y. If you enter 01-31-2014, Google Ads Editor automatically reformats the date as 1/31/14. However, if you enter the units in a different order, such as 2014-01-31, Google Ads Editor prompts you to re-enter the date in the correct order.