Hi! We are trying to create an operations calendar in Trello based on the known launch date of a product. We have several tasks that are tied to that launch date and need to be completed 1, 2, 3 etc. weeks prior in order to ensure a smooth delivery.
So far I've created a card for the product launch date (Titled 'New course') and included a checklist (called 'Milestones') with the other tasks that need to happen before hand. I've also implemented a Butler Rule so that when a card with the title = New course is added to the board, all of the items in the checklist are converted into linked cards.

This is working fine, however I have no idea how to add due dates to the linked cards that are based on the product launch date. I've looked around for answers and tried to create rules using the {triggercardduedate} variable but I can't get it to work. Could anyone offer advice? I'm very new to butler automation so screenshots would be helpful!
Essentially what I need to do is:
- Create a card with the launch date for the product
- Have cards created off the back of the launch date card for key milestones
- Have the milestone cards populated with a date based on the launch date e.g. Milestone 1 is due 3 months before the launch date.
Any help or advice would be greatly appreciated!
Thanks
cc. @Iain Dooley , @Dan Ivory (I've seen you've both posted on several similar questions so hoping you might be able to help)