2 Superdays in a row

Hiring usually takes longer than anticipated. To the best of my memory, the 4 accounting jobs that I've interviewed for (2 that I got, 1 pending, 1 lost due to budget cuts), none of them got back to me when they had expected to – “early next week” would mean Thursday, “end of the week” would mean Monday or Tuesday of the next week, etc. It's just the nature of hiring in my experience. Generally at least some of the people involved in the process are not involved in hiring full-time, so it's an added duty on top of the rest of their tasks. So, their goal is to make a decision by xyz time in order to get it done and over with and get back to the rest of their work, but some times they get to work on “make a final decision” day to find that their biggest customer's account has exploded and they've got to put out fires and do damage control all day, and before they know it, it's 3 days past the date they indicated and they still haven't made a decision.

That being said, I've never applied to or interviewed with Big 4, so can't say for certain with this situation. However, in the rest of the world, hiring is a slower process than anticipated for all involved…try to take it easy for a few more days before determining that you're toast.