Can you tell me the usual progression for vision loss with glaucoma?

It differs. The classic vision loss pattern is peripheral first, then more central as time goes on. Most people do not detect vision loss until there has been significant damage to the nerve. As well, some indiviuals may notice a larger than normal blindspot in their vision.
Often slow. Glaucoma progression is often slow hence the low rates of being noticed by patients . Some forms can be quite rapid however . It really depends on the type of glaucoma and the individual characteristics of the patient.
Variable. Asymptomatic at first, classically peripheral vision is lost first, but paracentral vision can also be affected early. Usually only advanced disease really affects the sharpness of vision. The higher the pressure, oftentimes the faster the progression once glaucoma is diagnosed and followed.