Dear [ ],
Quite a bit to unpack here. It turns out I'm going to address your question without concretely answering your primary concern: when will you hear back (more about this below).
Interview Best Practices
As best practice, I would strongly discourage anyone (so if you're reading this thread, feel free to take this advice on board) from soliciting feedback on an interview during the interview. Aside from the fact that it's unprofessional (as the interviewer very rightly said), it can come off as a bit creepy.
Think of it this way: you've gone on a first date (a nice dinner at a reservations-only restaurant) with someone impressive you've been sizing up for rather a while. You have some common ground, you establish; but three are a few awkward moments here and there. Now, the last thing you would do in this situation would be to ask your date how he/she enjoyed your company or seek assurances that there will be a second date.
Such action unfairly places the interviewer in an uncomfortable position (which makes things worse if you really believe you did not perform well), and risks having you come off as desperate.
Please, do not do this in your other interviews. :-)
Assessment of Interviewer
Unclear how to process whether an interviewer hates you right off the bat or not, but if so, you really cannot solve for it. What you can solve for is avoiding the temptation to project doubt about your performance onto the interviewer. Why? Because it hampers your own ability to be objective (which is critical when you want to play to strengths and solve for weaknesses in follow-up interviews) and diminishes the value of thoughtful self-assessment.
Speaking for myself, I have never heard a case where a candidate completed first-round interviews on a Thursday and had Decision Round Interviews with partners the next day. Aside from the fact I've never heard of this, I would be astounded at the logistical gymnastics required to pull that off. I have heard of first-round and Decision round interviews taking place in the same week: say, first-round on a Tuesday, and Decision Round three days later on a Friday. But this would likely be the case during the thick of on-campus recruiting by top tier firms at target schools. It could potentially happen off-cylce as well if the candidate were a high-performer in the first round and the interviewing firm was aware of the time pressures from competing offers. Otherwise, expectations to do first rounds on Day I and Decision Rounds on Day II have little basis in precedent or reality.
When will you hear back?
Unclear. I can only speak for MBB which is usually within 48 hours regardless of the outcome. If I had to speculate, I would say you can expect to hear back early next week.