Trying to set up an automation rule that moves due date back from set start date

[Josh Finley]

is it possible to create an automation where -

Trigger is

a due date is set on a card...

Then the action is 

Move the due date BACK 150 days from due date.   

our company gets start dates for construction projects and we have calculated a 150 day lead time for ordering product. so given a start date of, for example, 5/1/2024. I would like to be able to set the due/start date on the card to 5/1/2024. and then have the automation give me a new due date 150 working days prior to the original 5/1/2024 due date, giving us a drop dead date to order product by.  

[Daydreamer Mike]

HI @Josh Finley 

Yes, you would require a custom date field to make it work. Lets call the custom field

Start Date

Automation 1

When the due date is set in a card, set the custom field "Start Date" to {cardduedate-150d}

Automation 2

When the custom field "Start Date" is set, set the start date on the date in custom field "Start Date" 

You can learn more about custom field date formatting and arithmetic here:

https://support.atlassian.com/trello/docs/arithmetic-and-formatting-in-date-variables/