How do I know If my older dog is accepting of the new puppy?

Last week I unexpectedly acquired a year old rottweiler puppy. I already have a 10 year old female bully who is a little smaller than him. He wants to play all the time and she just wants to sleep. They have been introduced via parallel walking and are now seperated by a babygate . Ive been letting them around one another in short intervals so they can adjust slowly, they typically both have loose body language and wagging tails when on oppositesides of the gate. But when I say no to the puppy, or we play roughly the older dog will waddle over , whine and pace by the gate. Durring face to face interaction at first the older dog gets a little stiff, whale eyes and gets into his personal space until he rolls over then is back to wags.When he bats at her with his paws to play she will do a low unescalating growl. At first she was very unsure of him and was uncomfortable but its improving.How do I know if she dosnt like him vs she is just setting boundaries? How long did it take everyone's elder to accept the puppy? What can I do to make the introductions easier for them both? This is my first time having two dogs so any advice is appreciated .