"For example, if normally you could consider crossing Glen Pass on July 1, for this year would you prefer to delay until July 15 or August 1, or what?"
Unless you're a thru hiker, it's too soon to worry about it. Wait and see what the weather is like in May/June. If it turns real hot, like it did 2-3 years ago(I can't remember off hand if it was 2, or 3)when we had another heavy snow year, most of the snow will be gone by late July. If not, you're probably going to have to wait or go in heavy with ice ax and Kahtoolas. In any case, the trail reports will be coming well before July 1, in time for you to decide a couple of weeks before.