You won't find any specific item - Disney does not advertise, nor send out any media releases on this. The past few years, it's been during peak times: summer, Christmas and Easter, for instance. But, be aware they have been changing the dates each year. This year, the peak summer season was from first week of June - mid August, whereas last year, it was part of May, June and all of July, but no August.
All meals are current in the dining computers, so you just call up or go online, and you pay whatever that current price is. You can compare to see if dining surcharge is in effect with doing a dummy reservation for CRT - do an ADR for a non-busy time, and then a peak time, and you'll see the price difference.
You will never see the dining surcharge listed on a receipt, online or on signage, as Disney always has current prices in place. So, whatever the price of that meal is during your stay, is what you pay. Signs and menus are changed to reflect that.
HTH, Tiger
