Jim Macklin wrote
You have to have 1200 hours with specific hours break-downs
to take the ATP [USA] you can do the IR right away.

Section 61.159: Aeronautical experience: Airplane category rating.
(a) Except as provided in paragraphs (b), (c), and (d) of this section, a
person who is applying for an airline transport pilot certificate with an
airplane category and class rating must have at least 1,500 hours of total
time as a pilot that includes at least:

(1) 500 hours of cross-country flight time.

(2) 100 hours of night flight time.

(3) 75 hours of instrument flight time, in actual or simulated instrument
conditions, subject to the following: