Ours are not hang as such, maybe a few hours to bleed out, then we only take the breast and legs off (leave skin and feathers in carcass, also no gutting) and then coq au vin, or curry in the slow cooker. Usually do two at the time. My first hatch this year was 9 males and 5 females, so the boys will be reduced in numbers soon, one is starting to crow (they are 14 weeks now and mongrels of mainly maran with some RIR and Lght Ssx in there too).
For us it is usually not how old they are, but how troublesome which determines the swift end...
For roasting we normally rear a batch of proper meat chicks.