I've got a mixed flock of bantams, 8 hens 4 roos. when i decided to 'take the plunge' they'd been outside in their pen/coop for about 2 months or so.
they always sleep in the coop even tho i stopped closing the door to it after about a week. when i decided to let them out, i openned the door to the pen late afternoon (about 3 hours of daylight left). I was more worried about the dogs thinking 'dinner' than whether i could get them back actually LOL.
after about an hour or so they all had made several laps around the coop/pen, had met the dogs (on MY terms, not the dogs'), and showed no interest in wandering off. But i shoo'ed them back into the pen (with the help of a 3' long 1x4 board to act as an arm-extension) and closed it up for the night. The next day I let them out a bit earlier, around noonish and let them wander at will. I actually lost track of the time, and it was dark when i remembered to put them up. All but one had made it back home. the one being my sultan roo, who decided to camp out on a stack of pallets not far from the coop. so i picked him up, sent him to bed and closed the door.
since then they get out as soon as it's light (hubby opens the door on his way to work, just before dawn) and i close the door when i'm on my way to bed. thanks to my mini horses i'm also closing the coop door now, since the main door has enough holes in it to let my cats wander freely LOL (plans for a rebuild coming soon).
fortunately the dogs biggest thrill is to run mock 10 thru the flock and watch them scatter. they make no attempt to eat the chickies (even tho they eat raw chicken almost daily 8) they haven't put 2 and 2 together to equal FOOD!)
I don't know what to say about predators/hawks... we've had our share of possums and raccoons over the years, and i've heard some hawks overhead but knock on wood, no problems so far this year... the chicks hear the hawks cry out, and they head for cover instinctively... this equals the truck, trailer, horse trailer or blackberry bushes usually. i did witness my oegb hen flying thru the woods the other day with something overhead (guessing hawk) but she managed to find shelter and a bit later came running back home. it might have helped that i sent the dogs after her to 'go see'. maybe they scared off the hawk.