From starting a batch to where products are actually testable takes >3 months. "Risk production" means that the foundry says, "okay, we think everything is fine now, but we make no guarantees that it will work". Customers then have the option of purchasing super expensive wafer starts that might or might not work. You might luck out and have lots of great next-gen chips months before your competitors, or alternatively you might get the GF100 thing happen to you where you get five working chips out of each $10k wafer.
