Just to be clear, iDine right now is the name of the cashback program. (It used to be the name of the umbrella of all these dining programs, but several years ago they changed that to Rewards Network.) Very few people here use the cashback program (since we're on a forum called FlyerTalk and thus most like miles/points junkies!), and I don't know if it's different for the cashback program than the others.

In all the others: The official documentation is all wrong. It always claims you need 12 dines, but in fact you always need just 11 dines. I have no idea what it claims about expiration, but my experience in all the miles/points programs has always been, the moment I (re)qualify with 11 dines that year, it tells me I'm VIP through the end of the following year. As the year rolls over, it keeps me in the status I (re)qualified for last year, but says I now need 11 more dines to get that status. That simply means I now need 11 more dines to requalify for that status for the next year.

So if you have no status, the 11 dine qualify you for this year and next year. If you do have status, only after the turn of the year do you have to do an other 11 dines to requalify for yet another year after that.