How long does it take to learn to read Devanagari?
Most learners read simple words within four to six weeks of regular practice, and read fluently — without sounding out — in about six months.
This is the most predictable milestone in Hindi, because the script is
phonetic, finite and regular. Forty-four core letters, and once you know them
you can pronounce any word you see, which is more than English offers.
The realistic stages
Week 1–2: the letters, grouped by where in the mouth they
are made. Write each one five times; forming them physically does far more for
recognition than looking at them.
Week 3–4: matras, the vowel marks. This is where it
clicks, because every consonant already contains a short "a" and the marks
change it.
Week 5–6: sounding out real words, slowly and aloud, the
way a child reads. Unavoidable, and skipping it produces someone who
recognises words they have seen and cannot decode a new one.
Month 3–6: conjuncts — क्ष, त्र, ज्ञ and a few dozen more
— and fluency.
The thing nobody warns you about
The schwa. Hindi writes the inherent "a" but frequently does not pronounce it
at the end of a word, and sometimes not in the middle: नमक is namak,
not namaka. Native speakers apply the rules without knowing they exist,
which is why a beginner reading aloud sounds subtly off even with every letter
correct.
Practise this with a teacher
Reading an answer is one thing; being corrected while you say it is
another. EkGuru tutors teach one to one from
$6
a lesson, and most offer a trial.