Ken,
I was in an accident in 2004 and ended up with a hip replacement, so I have been through the same thing you are going through. When the PT people came in the next morning and wanted me to get up, I thought they had the wrong room, or were taking some of the drugs they had given me....It takes a while but you will continue to improve for a long time. Very soon you will only have pain or stiffness on the first few steps then it will be fine. That too will go away.
I always asked the PT people if in a former life they were recreation directors at Auswitz.....
Good Luck...keep in mind it get better and better