We processed 7 of our birds the other day. They were a few days over 8 weeks. I picked out the larger birds of our 170ish remaining birds (stupid, or rather smart foxes). I wasn't too impressed with their weights, they were all in the 7-8lbs range. However, I have been restricting their food a lot. I only feed them from about 10am to 4pm, other than that they are on their own. I want them to get out in the field and get some exercise. I know there isn't much to eat out there, but the exercise is the real goal. Dressed the birds weighed 4.5-5.5 lbs. Their livers looked absolutely perfect. Actually all their internal organs did. I was very pleased with that. We haven't eaten any of them yet.
I had been mixing grower (15%) and starter (22%) to keep the protein a bit lower to slow their growth but I am going to start feeding only starter since the rest of them only have 2 weeks left and I'm aiming for 10 lbs live.
My birds have had FF since about day 3.
Oh, I know everyone says to make sure you have enough feeder room to ensure that all the birds can eat at once. I don't subscribe to this method of feeding. I have about enough room at the feeders for 60% of the birds at a time. This causes them to have to fight for their food and increases their exercise. I do however keep the feeders full until all the birds have eaten and are sitting down with a full crop. It takes longer to feed them, but I like seeing them work for their food.