Hi Samantha,
I think i found a solution to this, you have to do it in more than one automation.
Automation 1:
Is triggered when customer fulfills an order - Wait 90 days - after 90 days adds tag ‘90DAYS’ to customer.
Automation 2:
Is triggered when customer tag ‘90DAYS’ is added - removes ‘90DAYS’ tag and waits 90 days again - after the next 90 days adds tag ‘180DAYS’ to customer.
Automation 3:
Triggers when ‘180DAYS’ tag is added… etc etc
I’m not sure if it will work, because I just created it, so I have to check back in 3 months to see if the follow up automation indeed starts as expected.

