I have 10 Cornish Cross meat birds from Meyer Hatchery that are 3 weeks old. They have been outside for 1 week with no heat. and slightly smaller than a softball right now.
The other pictures are from the last batch I grew out.
Ive been growing them slow on flock raiser 20% protein crumbles to prevent them from growing to quickly and having health issues or outright dying.
My last batch I raised grew out for 9 weeks and weighed 5-6lbs after butchering.