I agree with Arreau that I would not touch this with a 10 foot pole (two inexperienced dogs coming from such different places at the same time). But I also agree with Rowan that you can and should decide for yourself, and do what you think is best. In fact, I agree with absolutely everything that Rowan has said in this thread--a trial period, sticking to a schedule, dog's teaching each other--all great comments/suggestions.
With regard to introducing a new dog, they are both young and so my guess is that they will become fast friends pretty quickly. Maybe even immediately. When Cammie came to live with us, she was 8 weeks and Bob was 10 years. She took to Bob immediately. But Bob was not at all happy with this little bundle of energy bouncing around. It was fascinating to see their interactions, and I pretty much just let the two of them sort it out for themselves. Cammie had to be trained to understand me (clicker training worked wonders). But understanding Bob was something that came quite naturally. She understood every glance, every growl, every snap, every bark. At first, Bob would have nothing to do with her. But she went to work on him, wooing him gently and sweetly. After only 3 days she'd gotten him to the point where he would actually allow her to lie down next to him, touching him! Within a week, they were starting to look like best of friends. She'd crawl all over him, bite him, jump on him, try to steal his treats and he'd set the limits. Now he plants himself in the middle of the living room and she goes flying around the perimeter pouncing on him from behind a chair, from off the sofa, etc. Lots of snarling and the two of them are just happy happy happy. Unlike Sophie (my spoo who died in April), Cammie likes to snuggle right next to Bob when they are eating treats, especially long lasting treats like bully sticks or bones. Bob tolerates this to a point, but he has a low grumly growl when she gets too close to his mouth. Very cute.
My advice for what it is worth: (1) stick to a schedule (2) let the dogs work out their own relationship (3) don't put too much weight on how the dogs react on first meeting. It is likely to change as they get to know each other and to realize that they are going to be living together (4) You may need to separate them for training. (5) Have FUN!!!!