It really does take time. At least Maisie is not growling at Clyde, as my Chin did when I brought Bosco home. I remember thinking that things were never going to work out, but eventually they all made peace.
I know we all want the older dog to be as excited about the puppy as we are, and when it doesn't happen as we thought, it is certainly disappointing and worrisome.
I will say that Sadie, my smaller chin, would not look at Bosco for months. However, after quite a bit of time, I found them sleeping on the same bed, right next to each other. Sadie will rarely play with him, I think she finds him big and awkward, but every now and then they interact.
Bosco has become very good friends with Boop (my other chin), and they interact all the time. It took Boop well over a month to stop growling at him though.
I'll add that Boop and Sadie were together since they were 6 months and always got along beautifully from the moment they met. They were both about 5 years when Bosco arrived. Bosco has been with us for two years. I never anticipated that their reaction would be anything but pleased when Bosco came -- and it wasnt', so I have a good idea of what you are going through. Sorry this is so long, but it really does work out over time.
Joan