I think the “without aid” part is gonna be a bit of a loaded term here - in that I think I’m a decently competent reader, and if for some reason I had to fill in a form that said “can you read Japanese? y/n” I would probably fill in the bubble next to y.
But that said, my dictionary app of choice is never very far from my hand. I could probably get by okay without it in many if not most reading contexts, but I don’t choose to, since I can and do comfortably read anything I want to now using my preferred process that includes a dictionary.
I don’t really want to give exact numbers since I don’t think it’s something to benchmark, but I would say for me the “I can read whatever I want and it’s fun, not work, and it feels almost like reading English, and although I still have the crutch of a dictionary and anki it doesn’t feel like a crutch anymore it feels like a leg” point was the range of ~ a few years (from absolute zero).
And I would project into the future the point for me to be at “a native-like swathe of vocabulary, barely any caveats remaining” to be ~several years (if ever). There’s a whoooole lotta words in a language and you never really know what’s going to come up (saw the Japanese word for “islets of langerhans” in a manga the other day, for one). And where in English I’m well-read enough to just brush past a word I don’t really know vaguely assuming I get the general idea (do I know what “brocade” means, ehhhh…? maybe? I know the word and the vibe even if I’d struggle putting it into words and might be wrong if I did), with Japanese I still feel in a precarious enough position that I’m greedy to forge that confidence where I can get it, which is where dictionaries and anki come in. (if that makes sense).
The basic competency might be there, but the confidence lags behind, to one extent or another, and I imagine that takes a very long time to bleed in. And I guess what I mean is that “aid” may include help for confidence, not just competency.
I’m sure it also depends on what you read (I want to read many things) or what you do (I don’t talk to anybody in Japanese) and how consistent it is (I’ve been lucky to maintain a steady clip after starting) and what kind of process you like (I don’t mind a dictionary) though!
I guess at the end of the day what I mean is for me the “I can definitely read anything, and quickly enough to be practical and fun if I put my mind to it to boot” point happened surprisingly quickly (i.e. after a few years) (and felt like a palpable breakthrough - like I noticed it happen). But the “I can definitely read anything period, it’s not even a question” point remains well in the future.
I think you’re probably talking about that first, “can definitely read anything quickly enough to be practical” milestone? And for me I think it took a certain amount of practice, both in reading of course, but also practice in the process I like. At some point I stopped having to rip apart sentences to figure out how they were constructed and could see immediately which words were new to me in a sentence, and I could just throw them on the pile with all the other new words to learn.
At some point once you get enough used to how you read, the base sentence structures are absorbed and the pain points are more like the raisin in the muffin than the muffin itself, so to speak. And then you just get really really used to eating those raisins, I guess (I’ll accept the Metaphor of the Year award in the mail, thank you). I think it’s just practice to get there, not really dependent on a certain batch of vocab.
Does that help? Really not sure if I described any of that clearly… (except the raisins thing that was definitely clear)