So, just after the 2 week mark:
I can’t mount without a support, but I can ride 20 revolutions unsupported on my stock K1 Alien Backflip. How good of progress is this? (I’ve put in about 12 hours or so.)
and a question for the Unicycling community at large:
When can one say that he can ride a unicycle? Give your definitions, and would I fit into this category?
Cheers
That’s not bad going for 12 hours, well done:).
You can say that ‘you can ride a unicycle’ as soon as your ready to fall off in front of people.
Keep up the good work.
Well then mission accomplished haha 
My neighbors think I’m crazy. Oh wait. They’ve always thought that 
thanks!
I reckon it is as soon as you open your mind to the possibility that almost anyone “can” ride, and that everyones abilities are diverse, ranging
from riding one or two pedalstrokes to beyond. It is something you decide- most people who say “can’t” are responding automatically and are not trying to ride or do not want to try due to fears of injury or humiliation.
(Fifteen years ago) after two weeks of trying I started being able to ride places and felt like I had tipped the balance between can’t and can.
When you can ride and mount comfortably and in control I say you can ride. And yes, once you pass the “I don’t care what other people think” stage.
In addition to the ten familiar Unicycle Skill Levels (USA/IUF), the USA also has what’s called “Rider Level”, which is something like 0.5. It basically says you’re still a unicyclist even if you can’t yet freemount.
You’re there! Welcome!
And if you decide to stick with it, you’ll either be freemounting eventually, or not riding out in large open spaces free of stuff to hold onto. 
IMO You can ride when you are able to do it while thinking about something else.
Then yesterday was my first day as a true unicyclist, ended up lost in deep philosophical thought and I realised I was going in the opposite direction of where I meant to go! However before this I had done 20km…
I like the idea that it’s when you feel comfortable riding in front of people/around town, or even perhaps when it becomes faster than walking somewhere (although this may not apply to 20" riders, I’m not sure, those things are crazy).
Yeh 20" is just painfully slow.
The next stage is when you wonder why people are looking at you, and then you remember that you’re riding a uni.
I’ve heard is getting through Level 1, which is freemount, ride 100 m, dismount gracefully w/ uni in front.
I still can’t freemount, but I can Muni moderately tech terrain, and do a few tricks though.
I’ve at times had the opposite - wondering why people weren’t looking at me, then remembering I’m not riding the uni for a change…
Wow. Yesterday and today I did two things I wish I did when I first started: started riding witn no hands, and lengthened my seat hieght a good 4 inches. My control is bettter, I ride for as long as I have a straight path, and freemount progress is happened much more rapidly.