There is no rhyme or reason to their system of delivery times, in my experience. For example, in June 1995 the quoted delivery time on a CQC6 was 18 to 24 months, and 6 to 8 months on all other customs. The Viper I ordered then is still awaiting delivery. Meanwhile, I ordered the two ESM1s the day after Ernie first showed them. It was the first civilian order for them, so I think he delivered them as Navy orders got filled by making an extra one or two per big shipment.
I think there is a waiting period for each style of knife. 6's, of which he has the most backlog on, get made in large batches and most frequently. He told me that he intends to make a batch of 5's soon, too, to reduce the backlog on them as well. So a guy who's been waiting three years on a 5 or 6 may get it in the next few months. But a guy who ordered something like a Viper 3 or a SRT, which he may only have a dozen orders on, won't get a knife until Ernie sets aside time to do "odds 'n' ends". I really think he feels four years is the outer limit for most of the orders he's got in hand, and tries to complete them before they get older than that. And what-the-heck, no one's perfect!