Yes, it sounds like you're doing everything right. And don't worry, it is normal to be worried or nervous about your baby getting along with the new dog.

I've seen so many cases where people say a dog is dog aggressive, but its actually not true at all. Sometimes they didn't introduce them properly, sometimes a dog only likes certain other dogs, and sometimes they just didn't give it enough of a chance. A lot of people get scared when growling happens, but it is perfectly normal dog communication. It is much better to give that growling as a warning instead of just going straight for a bite. As long as the puppy will listen to Casey's warnings, she won't have to bite. Just watch them closely and give Casey lots of breaks from the little guy.

Lolly growls at my foster puppies all the time and she ends up teaching them a lot of manners