Paper tech is a meeting between the stage manager, the director, all of the designers, and the deck crew leader (who might be an ASM). This is the opportunity for the stage manager to write all of the cues into their prompt book. The idea is for the participants to run through all the cues in the show. Designers will (or should) come prepared with a list of all of their cues, but may add on as they see fit during the process. You should get through the whole show, which might take multiple meetings.
Cues will still change throughout the process, so be prepared to move, add, and remove cues, making sure to write down all changes in your prompt book. Use a pencil!!!
For student shows with student directors and designers, they will have a less concrete idea of where and what the cues are. This means you should go page by page, and sometimes line by line and check in with the directors and designers asking where the next cue should go.
Paper tech should be scheduled to run for at least an hour, but shows vary. For a mainstage production, expect around a two-hour commitment, while a student run show might be as little as half an hour (but you should still plan for an hour even if you think it will be shorter). If you're working with the Lighting Designer Jeremy Benjamin, he will propose a time frame. Like most tech things, you should be prepared for paper tech to run longer than you initially planned, and you might have to schedule multiple meetings if you're running way over time.