I think things may have changed over the years. I think I got 1000 subscribers within 60 videos and within my first year, but that was back in 2015/2016 and the algorithm changed in 2018 to follow watch time and audience retention more than anything else.
Theoretically you should see a snowball as you develop your skills and experience as a content creator, learning good thumbnail practices, watching your audience retention to see what gets people watching and what pushes people away.
I personally wouldn't expect to see much traction until 30 videos minimum. Some see traction far earlier than that, some won't see any traction even with 200 videos, so it's an individaul thing.
I personally think If you haven't really narrowed down what you're doing, and not seeing much growth by 50 uploads, that's a healthy time to re-evaluate what you're doing. I started seeing traction after 30 videos.
Audience retention percentages is what triggers YouTube to push your content. But you won't get an audience if no one is clicking, which is where CTR is important. You also won't see much CTR or views if your impressions are low, and for me personally, the best place to start getting impressions is under search with good keywords, good title and good overall SEO.
Once someone has been shown your thumbnail (the impression) it's up to the viewer to decide if they want to click (the click through) and if they DO click, if they stop watching pretty quickly (low average view duration) that will tell YouTube not to bother suggesting the video to other viewers. If it DOES get good overall audience retention (aim for above 50%) that tells YouTube there's potential in that video, and that's when they start trying your video in front of other potential audiences (boosting your suggested impressions) if you can get good CTR, and good AVD (average view duration) that's pretty much the ticket to victory from my understanding.
And of course.. the more videos you make, the more experience and opportunities you have to DO all of the above, and 30 is a good healthy number to start off with in my opinion.