I imagine that glass is harder to fabricate than metal or clay, so when did we start using it, and why? Was it marketed as more upmarket?
The general story is that the earliest glass use was during the Roman Empire, because that is when Syrian craftsmen discovered the technique of glass blowing. Before then, glass was primarily used in beads, jewelry and other decorative elements (I have personally uncovered glass from about 800 BCE Levant, and I believe it goes back well into the Bronze Age). I would not be surprised if glass vessels did predate glassblowing, but it would not have been common.
Within the Roman Empire glass was an extremely common material and is one of the most common find categories from excavation. Simple glass was apparently fairly cheap and mass produced, and should perhaps be thought of as something like a "lower class luxury". Some glass, however, displays truly extraordinary workmanship.