Hello Allie heart chickens,
I highly recommend you quarantine him for the two week minimum, for the health of your hens, but also, so that he can get to know
you.
If you plan on letting him run the place and have no problem with him flogging, pecking or chasing you, and, if you feel he is no health risk to the hens...then just pop him in with the hens.
I love roosters, and I really value my "Frito", he patrols the pen, keeps an eye on my girls, and teaches the newbies how to behave. But, not everyone has my philosophy on roosters. I have had 8 roosters of different breeds and personalities. All learned well.
While there are roosters with good personalities, there are some that are aggressive and do take work. The breed will dictate some of this. But, I believe it is the keeper that influences a huge part of the behavior.
With consistent training your rooster will not attack you every time you enter the pen or coop. You will be able to pick up a hen with out being pecked by him, because he will trust you. He'll know that you cause no harm and only good comes from you. He may even chose to spend time with you, like a dog!
You will also have to attend to your rooster's physical needs:
spur trimming (to protect hens backs), giving meds when he gets sick, scrubbing his legs if he gets scaley leg mites, etc. Yes, rooster's need attention too.
The first year is really the most tedious when teaching a rooster. His hormones will be running high! Having a rooster is just like taking in a pup. You would take time teaching it many things the first year, so that it can live with the family, right? At least you should learn about a rooster's behaviors before taking one on, then you can say, "Oh, that's why he does this or that."
And no, he won't hurt the hens. If they are older, they may hurt him! LOL! You see there are many dynamics involved.
So, there you go...something to think about.

God Bless!