Ahh The all so freq. question... Well we got our little ladies last April. Once they were ready to go out into their coop, they stayed in their until they got a little bigger.. Then we let them free range. We had all intentions of putting up a run.. But summer and fall found to be very busy... UNTIL,,, a hawk got my little Thelma, I was devistated..Soo we put up a 24'x18' chain link run with chicken wire on top.. It took us 3 days to get it done,, I kept the ladies in their coop til we finished..Which was today. We opened their little door and let them out... They are all stressed out... I wished we started them out with the run... So as not to stress them out AND not to have them as sitting "chickens" for the hawks..
So it depends on a few things... Where you live, neighbors close by, and whether or not you don't mind having chicken poop all over your yard, driveway, and decks...
They truely love being out and about,, But safety came first with us... Just wish we did it sooner...
Good luck