Answer: You must have your units set by Friday of Week 3 (5pm), the same as the Final Study List (add/drop) deadline. If you are taking a variable unit course, make sure Axess shows the correct number of units by Friday of Week 3.
It’s a common confusion that students think they can adjust units on a variable unit class until Friday of Week 8 (the credit/no credit/withdraw deadline), but this is incorrect. After Friday of Week 3, the only way you can change your total number of units is to withdraw from a class.
You can always refer to the Stanford Academic Calendar for details and specific dates.