white silkies...when should they lay

[tav1]

so my 3 reds @4.5 months old are laying but i also have a white silkie, shes not laying
yet.....all the same age. when do you think she'll start laying.?
her combs aren't developed like the reds......you think that maybe it?

 

[ChickenCanoe]

4.5 months is very early. Silkies aren't known to be very productive.
How much space is between the pointy pelvic bones. When that gap is 2 fingers width or more, laying will be imminent.
Also, days are starting to get shorter. This can delay onset of ovulation.