All four McKinsey interviews in one day. Any tips?

Look up crafting cases and do the free course, it's an excellent resource that will teach you everything you need to know about case interviews. More importantly, practice cases and your PEI with live partners who can give good feedback. You'll do great, good luck!

Others can share tips about PEI, case interviews, etc. but I'd be happy to share some tips about stamina (glad another commenter brought it up). Stamina will be critical, 4 interviews is a lot! For background, I went through long interviews myself, and also have over a decade participating and coaching competitive debate, which is draining in ways very similar to interviewing and those tournaments can go all day

I am highly confident in each of the below tips

1. Drink a lot of water during the day, and also the day before. You will not believe how much talking, thinking, and being put on the spot with questions will dehydrate you -- and dehydration lowers your performance materially, especially at the end of the day when you want to have a great performance at the end. 8oz of water in between the 3rd and 4th interview will not be enough -- I'd personally try to get a decent cup of water in between each interview and sip on one during
2. Get your prep done early, vs week/day of. It's easy to procrastinate, but you need to make sure you're prepared early so that (a) you're not as nervous day of, and (b) you don't have to stay up late working on or anxious about any kinks in your story or prep you're still working out
3. Get plenty of sleep, but don't use any sleep aids unless you normally use them - they'll probably make you groggy the next day. In general, avoid anything that'll put you into a materially different mental state vs what you're used to
4. Remember that the "interview" extends beyond the 4 discrete rounds -- be friendly with other candidates and avoid any sort of one-upping, rudeness, or inappropriate conversations
5. Try and walk / stretch. Keeping loose and blood flowing helps the brain
6. Okay I do have one case study tip that you should 100% do - if you're not currently really good at mental math, just practice core mental math skills early and separately from the rest of your case prep. Re-learning long division, long multiplication, basic times tables up to 10, and x% of y type stuff is pretty easy, but you just need to sit down for a few hours and get it done. In terms of immediate ROI of spending a few hours, separately practicing elementary math skills might be one of the highest returns. Different interviewers will value mental math differently (i.e. there are times you can get by with mediocre skills), but it's so easy to get good at with just a few hours and it will always make you look smart

A month is plenty enough time to prep if you work hard and practice (practice critically includes live practice with others, hard to effectively solo prep cases or PEI). If you feel like you're time crunched because of any classes, you might be surprising how accommodating some professors will be for extensions if you tell them in advance

Lastly, hopefully you find some comfort in knowing you don't need to be perfect. Despite what it may seem like, plenty of people get offers even if they made clear mistakes or could've done something better, and the bar is usually lower for sophomore programs since there's less expectation that you've done a ton of prep or career exploration

Good luck!!

For what its worth, I had 3 consulting superdays in 1 day, from like 11am to 6pm. There was a total of 6 interviews, each 45min long. What really helped was putting myself through that 5hr grind like 4 or 5 times before so that I could mentally get used to it. Also, I got to experiment with foods and felt that actually sugary foods like twinkies really kept me going so thats what I ended up doing on my actual day and it worked like a charm. Same foods might not work for you, but I'd definitely try that and other foods. Keep in mind that this is not easy at all, but best of luck - you can do it! 

ps. also skip all your classes that day

How have you gotten interviews this early?

If anyone is wondering, I had my super day today (four rounds back to back), and I heard back from an AP within two hours. I got the offer, and I'd be more than happy to help anyone else who wants to apply this year. Just PM me! (: