I didn't actually know how to use git when I landed my first full-time dev job. No GitHub account, no portfolio site. I'd been coding since I was 12 though, picking up HTML/CSS, jQuery, VBScript, C#, and SQL while running a BBS and writing bot scripts for MMORPGs. The code quality sucked, but people actually used what I built, and the feedback kept me hooked. Sadly that was all in middle school and I never kept backups.
A few weeks after exams ended, a few months before graduating with a Bachelor of Commerce (Finance Specialist), I went to my first developer interview at my university. After talking with the manager and team lead, they handed me a sheet of 12 questions covering logic, sorting, jQuery, and databases, and gave me 30 minutes. I aced most of it, stumbled a bit on sorting, and got the job.
My first project was a ground-up SPA rewrite of the University of Toronto's mobile map site. That was five years ago. Since then I've worked on projects for Facebook and Google through agency vendors, moved through Intermediate Developer, Developer, and Senior Developer, and I'm now an Architect at a cancer research institution. Still no portfolio.