The internship recruiting journey is a very personal one for each MBA.
For those who participate in diversity recruiting opportunities, such as those who identify as queer,women or of color, you may have your internship for the following summer locked down after participating in the early recruiting process.
Many firms seeking diverse candidates, hire for roles in corporate finance, marketing and corporate strategy roles through diversity conferences.
Some Investment Banks and Consulting Firms have created early recruiting programs the summer before you begin your MBA program. These programs essentially 'kick-off' the hiring of the larger class for banks and consulting firms so they'll have a pool of 2-30 incoming MBA students (depends on industry, firm and program) already locked into their firm a year in advance. Some programs offer fellowships to cover the cost of attending school.
I must note that these diversity programs are extremely important for many reasons. Yes, on the one hand they provide students from diverse backgrounds with incredible opportunities, but perhaps more important, they build a pipeline of professionals with differing experiences and backgrounds within firms which traditionally did not seek them out. This notion of inclusion is very important and we still collectively struggle with how to weave unique experiences into the corporate world, but these programs are a start. I recognize not everyone agrees, but I think this is a very important point to make.
If you are not participating in diversity recruiting, on campus recruiting is key. On campus recruiting comes in many forms and all T30 programs have some variation of the following:
Companies come to your campus multiple times throughout the fall/winter for information sessions, networking nights and eventually interviews
The companies and industries which come to campus will vary depending on whether your school is a 'target' or 'non-target'. For example, investment banks will most definitely actively recruit students enrolled at Columbia, NYU and Wharton, but possibly less so at Washington University or Wisconsin. This means that students in non-target programs will have to do more legwork to break into their target industry or company.
Second year students provide guidance and networks to first year students seeking out roles at the same companies/within the same industry
This is especially important for investment banking and consulting roles as second year students will be able to mock and case with first year students based on experiences they recently had as interns in those industries. They will also be able to serve as one of the first points of contact for connections to alumni at various firms in those industries.
Off-campus/student led recruiting
Career Services provides students with the tools and the network to seek out opportunities with different employers
Linkedin and other tools which require lots of time can yield great results, allowing the student to find the exact role they're looking for.