These cockerels will be in danger of acquiring "attitude" around age five to six months regardless of when they join the flock of hens. Their attitude has more to do with how you handle them going forward. And also your attitude will determine to a significant degree what their attitude toward you will be.
You can gradually integrate them now by letting them spend days in a safe pen in view of the girls. Then, over the course of a few weeks, let them spend increasing time mingling with the flock until you see they are accepted and everyone is interacting peacefully.
As for how to handle the cockerels in order to avoid them becoming human aggressive, the first rule is to keeps hands off as much as possible, only handling often enough so these two are used to being handled from time to time. Other than that, ignore them as much as possible going forward.
Here is my article on raising cockerels that might be of some help.
https://www.backyardchickens.com/articles/i-think-i-have-a-cockerel-now-what-do-i-do.76274/