I put them on the grill between 13-16 weeks, for that crispy skin goodness.....
....no, not much meat, but the grilled bones make a killer stock.
Anything older than 16 weeks, they go into the stew pot.
Have you harvested birds before?
No matter what cooking technique planned, always 'rest' the cleaned carcass in the fridge for 48-72 hours before cooking or freezing to allow rigor mortis to pass, or it may be too tough to eat no matter how you cook it.