@atl-lucas I’ve run into this issue before and it is sometimes confusing how to get this working because we’re so used to defining the Audience filter but in this case I believe your best bet is to use the Triggers to decide when it goes out, you can still define the audience but it’s not as clear because the audience isn’t filtered by the trigger -- this creates a bit of anxiety turning it on  you have to trust it’s not going to send out until that date matches, I do wish there was a way to preview that as well before enabling. 

To set this up, go to the same place you configure the Audience but look for the option Triggers >  When to send just above it and you’ll be able to configure something to go out based on an event or date.  Choose the custom data attribute and then choose the option “Before the date”

See below, here’s an example of sending out a notification 1 day before the card expires on someone’s Stripe profile based on the Stripe custom data attributes:

The only one concern I have, is that in the Intercom Help Center where it refers to this When to send feature it says it’s not currently possible with Emails & Product Tours but it works on all other types -- that being said, it seems to be possible to configure now from my rough test, maybe that note in the documentation is outdated. 

I have pinged the support team to check on that to let me know and I’ll report back when I hear or if you test it, let me know what you find out!  I didn’t get a chance to test it yet but I may give that a try tomorrow to confirm as well. 

Hope this helps!