The codes and rates are basically just the typical discounts they give to everybody. I noticed this a few weeks ago. My sister who hasn't been down in a few years got a pin code in email. I was all jealous, then a few weeks later Disney released the spring codes that are available now. They were the same exact discounts my sister got. Its like they do with everything. Codes come out for Visa cardholders, then a few days later, AP holders, then they are released for everyone.
If you want to know when a code will be available for you, check out mousesavers on the internet and see when they were released last year for the time you are going. They will be released around the same dates this year. I've been doing this for 10 years and have never gone to WDW without getting a code.
Edit: It looks like your going at the end of June. Last year the discounts for this time were released on May 7th.