Thanqol Learns To Draw!

[Glass Mouse]

Seriously, though, I've got no idea when to make the transition from drawing with to without references.

Short answer: Never.

Long answer: References will always be useful, no matter your skill level. If you look at some of the really good artists on, say, DA, they frequently use a reference for a difficult pose or a background or... anything, really. Even the people who are on "must've sacrificed their soul to dark gods to gain those skills" level.

As you get better at drawing, you build up a "library" of sorts; of things that you've drawn enough times that you can do it well from memory. They kinda live in your wrist. That library gets bigger and bigger, but it can never contain everything you'll ever need to draw. So whenever you have to draw something new (or just something you haven't drawn much), you need a reference.
References can also help you fine tune your existing library. Maybe you've forgotten how something looks, or you never got it right in the first place. So, basically, you won't need references anymore when you can draw everything perfectly. Good luck with that

Not that I'm one to talk. I'm usually too lazy to dig up proper references pictures. Tsk. That's probably why my progress is so slow.

Edit: Also, interesting to see the girl portrait. Everything seemed to be positioned so much more... right. Not gonna go into critique, though, because that's been covered in plenty