[matese]

I can just imagine your excitement. As far as it taking 3 weeks for Abby to accept this new comer that is not necessarily correct, it depends on the dogs. Each dog is different, it could take longer. I tell you this in case 3 weeks go by and Abby is still not confident being around the new guy, do not be disappointed and think Abby doesn't like the new lil fellow, she needs more time but, she will come around.
Rescues are rough because in most cases you never know their back ground, what they went through, if they were abused, lived on the streets before being found. Everything with a rescue is taken in baby steps. When they come to a new home there are many adjustments they will be going through. New smells, new sounds, new routines / schedules, new BFF and new humans. That's a lot for a dog. First you have to gain their trust. It will be an interesting ride for sure lol.
I was very lucky with my rescue, he was a surrender, not an abused dog and came to me spoiled rotten. His was surrendered for financial reasons, he bonded with me the day I took him home. I know his entire history because his prev. owner asked, who ever adopted him would they keep in touch and let them know how the dog was doing. I did do that, 5 years later I still text and send pics of him.

Not everyone is as fortunate as I was.
You will do just fine, you are giving a precious baby a 2nd chance in life, a good, loving, secure home where he will be spoiled as he should be.
Looking forward to photos. Have you selected a name yet.