I don't really have time to dispense with the last nine so let me just cut to the chase and tell you the Number One Reason For Not Waiting Until The Last Second To Meet With Your Accountant Before The Tax Filing Deadline.
Because we are all nuts - sleep deprived, stressed out, on the sheer edge of utter panic, hitting the wall, fed up with questions, queries, and interruptions, working so fast that you've got to be worried about accuracy, worried about accuracy so much we no longer blink, not eating, not sleeping, and finding it hard to put sentences together.
At this point in time, "8" is a joke worthy of a laugh. ("6" is pretty good but not as funny as "8.") We are moving so fast the computer can't keep up - and this is no exaggeration - we are moving so fast the computer needs to reboot to get a grip. I kid you not.
So, if you feel pretty confident that you have an easy return and that there aren't already 100 people in line in front of you and that a zombie accountant is really a good thing, then go ahead. Wait until the last minute.
On the other hand, if you want to see a head explode....