Any Professionals have tips for installing windshields?

I was told when I bought a new gasket for my 68 dart that the first time the gasket is used no extra sealer is required but is optional. If you re-use the gasket then a sealer is required.

I installed the new gasket with no sealer and I have checked it after the few snows we have had and no leaks so far (there is no carpet in the car so I can see the floor).

After I installed it, I let it sit in the sun for a few days and settle in where its going to stay pretty much.

Cant say I have ever re-used a gasket, most used ones here are cracked and have a white crust from dry rot.