It's a fair question that a lot of people are asking. I think it's possible that your November start date gets pushed back. Fundamentally, you need to ask HR what to expect.
That being said, the odds of a pushback dimish over time. I.e. It is more likely that Sep-Dec 2019 start dates are pushed back than Jan-Mar 2021 ones are. However, I do still believe pipelines have stabilised across most offices.
Assume you'll have a delay and you won't be disappointed
Send out feelers to see if you can snag an internship or part-time job...the extra experience, income, and backup, are all good to have.
Prepare for the GMAT/GRE (if higher education is any future possibility)
Data Science is a growing, important, and marketable field that I highly recommend gaining skills in. You may not have to get a full certificate (though it is an option). There are many one-off classes that you can group together (i.e. a database design/structure class, SQL class, Python/Ruby, Tableau, Data insights/visualization, etc.)
Attend an academy to hone your skills - There are lots of academies out there that prepare you for the real world. Not a bad use of time to get skilled up so that you can hit the ground running at Bain and rise up the ranks even faster! (Feel free to PM me if you'd like to know of a few)