How to change text (date) in post base on the day

Question

So the question seem unclear, i rewrite it to hope for the best and get some great ideas.

I write a WordPress Sticky post (always first on top). In that post text there is something written like : Act fast, enroll in the next class. next date : sept 10 2012.

But as time past, date changes, and to keep that post current date must be change. So where I can put a list of date, and automaticly change the post date (text) according to the next date base on today date...

what plugin of php code can do that... i think shortcode can do that, but what your way to fix that ?

-- example listing of date :

• sept 10 2012
• sept 30 2012
• oct 5 2012
• oct 22 2012
• ....

based on that example, let's say today it's oct 1st, so i like the post to read : Act fast, enroll in the next class. next date : oct 5 2012. So like that the date list ignore the past date (to late the course is done) and show the next date based on today date, and let people know... hurry, it's soon or never. I know there will be other date, but the customer dont have to know that !

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Editors note: For clarification, here's a short explanation what the OP is asking for.

• A post has multiple "dates".
• Each date represents a change to the post content.
• When a date passes, the template should autom. recognize that and switch the content.

Disclaimer: This is what I've understood.