For me personally it took 2 months to "fully" adjust (meaning I can type without looking at the keyboard but every now and then I make a typo and need to correct it). I used this -> https://www.keybr.com/ almost every day. You can just set preferred layout without actually changing your keyboard's settings and it have very nice "teaching" sessions. Tbh I don't notice a huge difference, its more comfortable but sometimes I have a brain lag when I need to type on my phone since its on qwerty. Ergo layouts tends to be worse on mobile (because ergo usually have common letters close to each other and its not very cool on a small screen, qwerty is suprisingly one o f the best for smartphone's 2 thumb style)

About two months of typing. If you are remotely ever interested print out a keymap of Dvorak and have it somewhere visible. Just seeing it over and over and over again will build that familiarity. Just do it today, even if you'll never end up trying it.

Without that it took me like two weeks of it actually being painful where I was closing my eyes and mentally moving each finger deliberately. After about 6 weeks I got to 30 WPM which I felt was sufficiently fast to work as a developer unimpeded. 2 years later I'm up to 60 WPM which is faster than I ever was with QWERTY. What I do is three 120 second long sessions of www.MonkeyType.com at lunch each work day.

Colemak user, maybe a comparison: 2 weeks until I could "type" but it was frustrating as hell. About 1 month to 70wpm, which was the bare minimum where my thoughts would no longer outrun my fingers. After about 6 months I was back at 110-120wpm consistently, but ever since then I notice that I'm regaining little micro-skills I remember having, like hitting the right key upside down with my left hand while walking past the desk. So I suppose the learning never stops ;) About 7 years now.