Interior trim before or after glass install

The dash has to be installed before the windshield goes in. Otherwise you won't be able to access the hardware.
My headliner/glass guy installed headliner first, then gaskets, then glass. On my 69
barracuda the inside lip of the glass gasket covers and overlaps the edges of the headliner. As CudaChick 1968 said the metal dash has to go in before the windshield.