You can take the exam before you graduate or afterwards.
(Speaking from experience) the closer you take the exam to taking your college courses, the better.
Some colleges/departments provide funding to assist with taking the exam if you do it while still a student.
Register for an FE exam by creating a MyNCEES account. Registration is online.
There is a $175 testing fee.
Penn State's Dept. of Architectural Engineering has an Fundamentals of Engineering (FE) Exam Support Award. AE students who successfully pass the FE exam before they graduate are eligible to receive a $100 award from the Department of Architectural Engineering.
Where to take the exam
There are limited locations where the FE exam can be taken and it must be at an approved testing center. The test can be scheduled at any of a variety of testing locations within the country.