Change in View-Through Conversion Window
Starting March 29, 2017, default window for view-through conversions will be updated from 30 days to 1 day. Here to keep in mind is that default window is for 1 day but you still can select different window if you do not want to track for 1 day. 1 day default window will report conversions that happen within one day of ad impression as view through conversions.
This change will be applied to all accounts that has default window set for all new and existing conversion actions. If you have already selected and not having default window, it won’t affect your account. But if default window is selected, you need to change conversion action.