How long should I wait?

[chicknsnbiskits]

I have 4 pullets, 3 of whom are laying frequently, even in this bitter cold. They all started before their 6-month birthday (which was last week).
Just our Golden Polish, Basia, is holding out on us. She's become the noisiest little girl, though. Squawks and honks and growls all day long. Is this the PMS before laying???
At what age should I decide she's not going to lay? (Impatience, I know...)

 

[LynneP]

I'm sure Polish owners will chime in. I'm guessing at best- sounds like she's getting close...