When you join the course, keep in mind that it will have a significant impact on how you spend your time in Mumbai. If you opt for their flagship PGDM course, expect a rigorous academic schedule that demands a lot of attention, especially if you aim for good internships or placements. Luckily, the location is perfect for any kind of exposure you wish to gain during your stay.
While the initial traveling may be a bit of a hassle, it's important to get used to the local train transport as soon as possible because it will become your life and soul. The city of Mumbai provides you with enough opportunities to go out and explore, which you will need to do from time to time. Keep in mind that the cost of living and traveling can be a bit high, so make sure to cross all your Ts and dot all your Is before you move to the city.
You should remember that space and silence are a luxury in Mumbai, and not everyone can afford them. However, it's going to be an incredible experience overall. Once you get used to the fast-paced life of Mumbai, you will have an awesome time in the city.