How do I get hired through my externship???

Hi! I'm about to start a very coveted externship (unpaid of course) at one of the top 2 major dialysis companies as a dialysis technician. This is a brand new partnership between them & the school I just completed and not everyone was offered the externship. Apparently I have still have to interview, take a drug test/physical, backgrounds checks & I filled out their regular job application & forwarded my resume & do most everything their brand new techs do, this is up to 120 hours of training. I feel this is a win win because no matter what I will gain invaluable training in dialysis for my resume but of course I'm hoping to get hired. I figure if they like me all the paperwork is completed, but am wondering if a job offer can possibly come before the 120 is up or do companies wait until the last second. I'm still job searching just in case but I've never done this before so don't know how it works advice is appreciated, thanks!