4 years after graduation: Breaking into Investment Banking

Hi I am currently doing an ER internship at a MM in my home country. Currently, I have an offer to go to study Finance and Accounting at Imperial Business College Business School for this academic year (2019). Recently, I am contemplating on whether I should start my masters this year or take a gap year and do off-cycle internships at a PE or IB (there are several opening that have come up and my seniors have recommended me to several of these roles).

I am dead certain on doing a Masters in Finance now or in the future but the main concern for me is that I have graduated in 2016 and have already deferred my entry from last year. If I decide to do another gap year and start masters in 2020, assuming that I get into one, that would leave me 4 years without any full time experience (2 years of mandatory military service + 2 gap year).

Can anyone shoot me with some opinions or insights? Much appreciated.