Depends how quickly you need to do it and how fast you want to get the edit out.
In AE, on the clip, there is a drop down. Go to that click it go to time-remap.
What i'll usually do then is use the Pen tool, mark the point where I want to have the shot play back slow first. Then set another point about 3-4 frames prior to it.
Then what you can do is go back to your normal mouse button, and raise/lower the bar up and down to get the desired speed.
Or you can send it to AE through Dynamic link or just turn it into a composition, then save that project file and as soon as you save you'll have to render that "composition".
Or you can actually export, open in AE, export, and re import to PP. I tend to have quick edits to get out the door and just use the first method. if i'm trying to be more precise I'll use AE.