As anyone who raises chickens will tell you, no watched pot takes longer to boil than one watched while waiting for young pullets to lay their first egg! Generally, chickens come into lay at about 20 weeks.
Our 'Tweens' started laying today, at 18 and a half weeks. These are ISA Brown pullets that we got last February. We all them 'Tweens' because we have chickens that are much older and another batch of pullets that are five weeks younger.
Between now and August, we'll have 16 chickens coming into lay, so I'm glad to have found the first floor egg! My egg customers at work will be delighted. :)