Corporate finance internship to IB for FT

I am a junior at a target school and >3.9 gpa (finance/econ + STEM major). I have an internship for this summer in corporate finance at a good bank (think ms, boa, jpm). My goal is to break into investment banking, but I never recruited for IB internships because I didn't start looking for positions until the fall. 

I have looked A LOT into what it takes to make this switch, and I have already started networking (both with distant connections and cold emailing school alums for "informational interviews") and preparing technicals. My question is really HOW to actually do this. Officially, FT for IB recruits in the fall, but I also suspect that I don't want to give up the leverage of my return offer at my current bank. I thought this may be a common issue, even for current IB interns looking to switch to a different bank. Does anyone know anything about this? Is there recruiting in the summer before current internships are over? Do I realistically have a shot of making this happen?