i am new to chickens and my first flock is seven chcieksn. Two are white leghorns who both been laying one egg each for a month now but my other five are not. They are Wyandotte s and Rhode Island reds. They have not laid eggs yet. No Brown eggs only white eggs. They are all 20 weeks old now. Am I jumping the gun on them? How long should it be before I should get Brown eggs?