Introducing a New Ferret Question!

Hey! I'm new to the forum and also to my new little girl (who I have had for 4 days now!). I rescued this little girl who is a 2 year old female. She's pretty underweight but extremely friendly and full of energy! The people who owned her before me hadn't let her out in over 6 months so I expected some behavioral problems but so far haven't had any. She's been sneezing quite a bit so we have a vet visit Friday. I want to stress I will NOT be getting a buddy for her until she has her health cleared by a vet and has gained the appropriate weight! However, I do think with the amount of energy she has that she would do MUCH better with a friend. I've been reading about how to go about new introductions but I'm curious what the best age ferret would be best for introductions. I'd prefer to have another female, although I'm reading that two females tend to be more aggressive with one another, is this the case? Main questions is what sex should I look at getting and should I find a ferret close to her age or adopt a younger kit for a better introduction?! Thanks so much for all the help!

Hi again    
Generally, females do have a worse reputation for accepting another female.  They can be territorial.  I'm experiencing that now.  But mostly my current troubles are between Lola and Rosa, the two latest additions, both of whom had no room mates before I got them.  
I would say that in your case, sooner is better, before Aster has been there long enough to really  establish her territory, say in a month or two.  If possible, go for a ferret around her age.  Kits may get picked on.  Also, if possible, bring Aster with you to meet a prospect, and see if they hit it off or go at it.

THE DOOKS OF HAZARD