I think it depends on how old they are their first spring. Mine was a year old in the spring and that is when she started. I have one the is about 6 months now so I don't expect her to start until the weather starts getting a little warmer next year.
Pekins are a meat breed, so generally not heavy layers. Some lines have been bred to lay eggs, so how much your Pekin lays is going to depend upon what strain of Pekin you have.
As to what age they start to lay, they lay whenever they are darn good and ready.