Depending on how many you get, you can pen them for a number of weeks and let one out and keep the other in.
Then when the one is happy with coming back to the coop or barn you can let another out.
Adult Guineas take a bit of time, 8 week old take a whole lot less time to get this done and
this is the age I look for Guineas when I buy them without raising them from keets.
Guinea fowl seem to be babies until about age 12 weeks. Adults WILL roost in your trees around
your property and then eventually roost in your barn with the rest.
The best thing to do it get about 6 or so use to coming back in to roost and you can introduce other Guinea
fowl into your flock and they will roam with yours during the day and eventually come to roost with them.
Guinea fowl DO NOT like to be alone and they will gravitate to any Guinea they see. Females are especially important
to have around as they call to the others. I use a really large cage and let the other Guinea around them when I am
introducing new ones. Keep your new ones in a safe environment, if you can get them up high in their cage they tend
to not freak out so much as they roos as high as they can.