I really didn't get what's going on with this post, but maybe it's just because I am too dumb.
I think it would be easier to introduce a baby to an adult, but by introducing 2 adults you'll probably have no problems with puberty. I believe it's up to you.
My boys get along just fine and (I really don't know when they can be considered adults) the first introduction was with Stephen, 2 months old, and Scott, and a half moths old.
Now I introduced Rasputin, I have no idea how old he is, but the vet said about 3 months, to my boys one month after the first introduction. It was fine. No problems at all.