B-School after 2yr ib or 2yr ib + 2yr pe

It's tougher to get a post-mba pe position w/o pre-mba experience. So, bluntly, the former. Next in your order would be post-mba pe associate. This subject is all over this board. Do a search

It's easier to get into some of the MBA programs, though, if you're 24 or 25. (For others, it's easier to get in if you're 29 or 30). So there's a bit of a trade off if you have your heart set on certain schools.

But yes, consensus says that if you have your heart set on working in a certain field, it's best to enter that field before you do your MBA or other graduate degree if you have the opportunity.

I also tend to agree with IlliniProgrammer.

If you have the opportunity to do PE, I don't know why you would choose Bschool. Making money vs. spending money. Bschool will always be there but PE might not. You might not even want to go to bschool after a couple years in PE especially if you can move up without an MBA.

Which MBA programs do you think are more suited towards older candidates (with respect to the top 15 or so programs)?

Chicago, Northwestern, UPenn.

Harvard and Stanford typically lean younger.

*: Heard this second-hand from a 30-year-old MBA applicant, so I can't guarantee its accuracy.