Information on amount of fertilizer, formulation and frequency of application varies widely. On vacation recently in Hawaii , I just spoke to a woman who grows bananas. OK, so I'm back to where I started. Whatever you use, make sure it's a lot. With all the watering, fertilizer is also washed away.
Bananas are heavy feeders which supports their fast growth.
I also have discussed banana growing with a man from the Philippines. That's my plan this summer. One other thing about fertilizer, particularly the non-organic kind. This becomes more difficult as the banana grows and the pot starts looking ridiculously small. At this point, my own banana plant is just a wad of roots in its pot with very little actual potting soil remaining.