How much space you need depends on a few things. Type/size of breed. Do they free-range part of the day. Things like that. General rule of thumb is 6sf per bird. Of that number 2sf should be inside of the coop and 4 sf of run again that is per bird. So that is 120sf of run. This is also a minimum you can and where possible should try to give them more space. Hope that helps.
The MINIMUM amount of space hens need in a run is 10 sq feet each for 30 chickens you would need 300sq feet (30 x 10, 20 x 15 etc). More is always better! You can start introducing your chicks outside now if they are feathered up. Give them some heat during the night if you can to introduce them more gradually. Pine needles will be fine.
I didn't make these numbers up. I personally have not built a run yet and my chickens have access to my side yard that is much larger than any of these number. So I cannot speak from personal experience as to how they behave in this size run. That said I read several chicken books before getting chickens and these are the numbers I often ran across. If you look at the pre-fab coops at your local feed store these are basically the dimensions they are using.
Lots of chickens live in these little pre-fab coops and do just fine. Is this how I choose to house my birds? No, but I won't say someone who does buy one of these and keeps their birds in it are wrong either. Industrial farm chickens get 1sqft for their whole life. I believe 300 million birds live in battery cages in the US alone. So if 6sqft is all that someone can manage that is still a MUCH better quality of life for the birds than if they had bought eggs from the store.
As I said before if you can by all means go larger. Personally I like letting them free-range but I have a fenced yard. Take what you have and do the best you can. Good luck with your new birds!
Actually there are no magic numbers for space requirements that cover all of us. We keep them in so many different conditions and climates, with different flock make-ups, using different management techniques, and for such different goals that no one number can possibly cover us all. It’s also not that important if the space is in the coop, run, coop and run, or some other way. What is important is how much space is available when the chickens need it. You can follow the link in my signature to get my ideas on what should go into the thought process when deciding how much space you need. It’s sort of written with coop in mind but the concepts are really based on total space available when needed.
Commercial operations do often use a total of around 2 square feet per chicken in a coop with no run, but they also normally trim their beak to prevent them from eating each other. Beak trimming is one management technique you can use to help shoehorn them together. But if you trim their beaks, you need to feed them mash instead of crumbles and pellets. It’s hard for them to pick up the individual bits of food. You are looking at a system in raising them. That’s a system most of us on this forum don’t use.
You don’t mention anything about your coop, management techniques, flock make-up, or climate so I have no idea how big your run should be in your unique situation.
You don’t say where you are or what your current weather is like, but most chicks are fully feathered out at five weeks. Weather is probably not an issue for you. I assume they are currently in the coop and are used to the coop as home? At five weeks you can just open the pop door and let them decide when they want to go into the run. Sometimes most of mine are in the run within 15 minutes but usually it takes a lot longer for them to get brave enough to go outside. I’ve had some go several days before the first one ventured out. Each flock is unique.
It’s kind of funny to watch them. The bold ones will peek out the pop door and be curious, but it takes a lot of courage for one to actually attempt it. After one goes out, the others usually follow but the interaction and flock dynamics are fun to watch, even at that age.
Their first few days they may stay out in the run instead of going into the coop at night. You need to check on then after dark and put them into the coop until they get used to doing that on their own. I’ve had some that did it by themselves from the start, but it is more normal that a few take a few lessons.