Change Post Categories After Date/Time

In preparation for the impending bad weather this coming Monday, I’m adding something to a non-profit radio station’s website using Gravity Forms so that local schools, churches, etc can put in their delay/closing information.

Once this information is automatically published, I want it to change category from “Closings” to “Expired” (or something like that).

I’ve tried several plugins but since I’m using Gravity Forms to create the post, the “Post” function never fires in WordPress, so none of the plugins will automatically change or expire the post – nor will they set whatever they need so when a cron job runs they should perform.

So, I’ve played with a lot of PHP code trying to get the category to change. I have a hidden Custom Field that denotes when the post should change/expire, but every bit of code I’ve tried so far gives me errors and actually takes the site down.

Anyone have a code snippet in their bag of tricks that might work for this? I’ve got it posting automatically, so I can just manually do this for Monday, but it would be nice if I could go ahead and get it going automatically.

I also have their site automatically posting Nixel Alerts using the Postie plugin, but it also does not fire the normal “Post” function so those will not automatically expire/change. If I can figure one of these out, then I can kill two birds with one stone.

Thanks for any suggestions that anyone has.