Hi Teresa, We like to let ours sit at least 24 hours at Refrigerator temps before cooking, We usually process ours and then shrink bag them right away most are always stiff getting them into the bags, then we deep freeze at -5 to -10 Deg F. When we eat them we let them thaw slowly in the refrigerator for 2-3 days and they always turn out perfect, brine them is even better. I'm sure there are some people around here who know some hard science on Brine Vs. Time etc if you need to know for sure.
Most people seem to say to let the rest for a 24-48 hours period in an ice bath or refrigerator, but we never have any issues freezing them first. Age can make them tough but not until after 9 months or a year or more for most breeds IMO. On our layers we cycle them out every 18-24 months, these are smaller birds at 3-4 lbs usually and we make large batches of pressure canned soups from them and they turn out pretty tender.
What kind of birds did you raise? 2.75 lbs seems small for 15 week old birds unless they were a smaller variety/light breed not meant for meat?
I just processed some Pioneers that were pasture raised with supplemental feed/sprouted fodder. They averaged 5.03 Lbs for a mix of hens/roos. the largest rooster was 6lbs in the bag at 15 weeks & 3 days old. Hybrid birds can get huge if they don't just outright die on you, have a friend who swears by his CX and they average 7-9 lbs each for a 16-18 week bird, but he has allot of losses too.
