You would know more than me, but fall foliage to me doesn't really vary more than a week or so either way. It can start late but then it usually finishes within a week of normal.... or it can start early but still finishes up around the normal time. Like it really wants to find the average dates... which I tell people on the mountain is usually the end of the first week of October, and in town it's like October 10-15 time frame. Columbus Day weekend in mid-October is always busy with tourism traffic and is always too late for mountain foliage but under 1,000-1,500ft you can usually catch some straggling colors.
But when folks throw out foliage as being either 2-3 weeks late or early, it is just simply hyperbole because that's like a peak in mid-September to Halloween on either end. It just doesn't happen.