What kind do you have? I have French guineas that I processed at five months and some I recently did at eight months. The last ones were 5-6 pounds and as fatty as a duck. They grilled up (gas at low temp) just fine after an overnight marinade. Frenchies eat a lot gain weight and are not good fliers (which on the down side makes them easy for predators.). Mine were so fat that their livers looked like fois gras. I was afraid to eat it! Their meat was succulent. Overcooking makes for dry meat even in stews. Not so good when cooked to falling off the bone. Sauteeing works just as well. And in my experience, the tick/bug control issue is overdone. I had thirty guineas this year and picked more off myself this year then ever before. And so far as Japanese beetles and June bugs go, my welsummers put them to shame! I might try some more this fall.