5 year old Chi needs to be spayed?

I just brought her home from my sister. My sister got her from a BYB a few months ago. I want to get her spayed ASAP, but do I need to wait til she is more adjusted to the family? Most of my other dogs I have had spayed/neutered were mine for a while before I had it done. Just wondering what the precautions might be with her being in new surroundings. Not sure if it will affect her. My sister said give it a couple weeks and then take her. It is just about time for her teeth cleaning again in about a month, but I would like to get it all done ASAP so she doesn't come in heat. I am not going to breed her, and my sister didn't either, but got her while she was pregnant and didn't know it. She was severely abused, so my sister gave the guy like $50.00 for the dog. She is so sweet. Just wondering, is there anything else I need to be aware of with her have been a breeder? Any help is greatly appreciated! I have never gotten a dog that was at this age, all mine were still younger