From my own experience, I prefer to have at least a year with a new addition before I consider bringing in another bird. That gives time for the honeymoon to be over, and for issues that a mature bird might be bringing from his previous life.
If you bring in another bird, will you be able to give it the one-on-one attention it needs without taking away from the time you already give to your existing flock and animals?
My Hahns, Beau, is a real sweetie, but she is far more needy than my other three, and indeed than any other bird I've had. If she had her way, she'd be permanently attached to me! She's gone through a lot of change in the time she's been wtih me, which is about a year and a half now.
Abby