Only an hour to change the screen, the other hour is the curing time. The glue needs to cure properly, and the car needs to sit still for that to happen, in order to be safe to drive. 1hour is the minimum driveaway time for a car with more than 1 airbag. If it's less, and you were involved in an accident where the airbags deployed, the screen would not be stuck well enough for the airbags to work (they work by inflating and using the screen to keep their position)
Creaking is to be expected on most car, especially ones like our Lexus' and Toyota's that have a hard compound trim around them. This needs time to bed in and seat itself. It's faster in summer to do so, as it;s warm and the black trim soaks up the sun, making it supple. In colder months, like now, it will take longer.