The length of time it takes to have glasses made varies considerably depending on the lens used, and unfortunately completion times can not be guaranteed. Lenses that do not meet quality control need to re-made from the beginning. If you feel you would be in a desperate situation without your glasses for a few days, perhaps consider having a spare pair.
Stock lenses generally take around 4 business days, although urgent orders may sometimes be completed next day in the afternoon if ordered in the morning.
Other lenses usually take around 5 business days, with urgent orders taking at least 3 days. Antireflection coatings take an extra 4 days minimum, and other treatments such as tints also add an extra day.
Some specialty lenses need to be ordered from overseas, and will take longer, as will complex prescriptions.