I used to be a technician at autoglass, and theres alot that goes into changing the glass on any car, the obvious of taking the trim off but the cutting the glass out isnt that simple as it needs to be very carfull not to cut into the chassis, then the new glass needs to be prepered or if recycling old glass that also needs to be prepared.once prepared tye special adhesive mix needs to be applied, first a primer and then bond onto the glass, then lift it in and make sure its square on in the frame.
As for waiting times, depending on the car but being a puma the glass isnt that heavy so an hour should be fine to leave it
There are some pikey methods of cutting the glass, a stanley knife will do but be very carefull not to cut the frame, also ALL the old bond needs to come off and needs to be smooty and flat as possible