For many eye conditions where the vision loss is slow (and painless), it can take a few years. Especially with field loss, people can compensate by turning their heads a little more... but as the field loss grows, turning their head by itself isn't sufficient anymore.

I’m 22 and I found out like last week that I’m blind and that “legally blind” is actually a pretty serious disability when it can’t be corrected easily. I can wear glasses but the migraines aren’t worth it.
Always just said I have “shitty vision”. But...I don’t have depth perception and I can’t read anything unless it’s in front of my face. Also can’t see facial features from a few feet away. My whole world is very blurry lol.
Still kinda getting used to it. The fact that it gets worse year after year is a bit scary.
But! I’m learning all about accessibility and just recently made some changes to my phone so I can read/type without giving myself a headache and getting severe “text neck”. I’m not so scared anymore about going more and more blind because of this subreddit and all the things I’ve learned!

I’m not VI myself but what you’re describing is described to me frequently be clients. It often seems to happen when a specific item is no longer seeable or when an eye doctor diagnoses the eye condition. Particularly people with eye conditions like retinitis pigmentosa, stargardarts, diabetic retinopathy and glaucoma talk about this the most.