When is my 21 week old leghorn going to start laying?

[Egg_cited]

Her comb is red she does squat. She also has been curious around the nesting boxes. Her sister started laying two weeks ago. How long is it going to take?

 

[Tookie]

Try and check her pelvic bones.->
https://www.backyardchickens.com/articles/who-is-laying-and-who-is-not-butt-check.73309/
She should be laying anytime.

 

[nuthatched]

When she's good and ready and not before. Stop checking, she'll lay the next day. Chickens live off spite.