Answer:

You can see which exams you are eligible for, when you can take them, and schedule your exam from the F5 Candidate Portal (http://certification.f5.com/).

Simply click "Schedule an exam" on the home page or "Scheduling" in the top-navigation bar.

This will show you a list of exams you are currently eligible to take under "Open Exam Eligibilities", giving you details for each exam.

You can schedule any exam listed under "Open Exam Eligibilities" and take the exam any date between the "Earliest test date" and "Exam Administration Ends" date (inclusive of those dates).

You can start your recertification journey 90 days prior to your certification expiration date. But, not before that. 

Example:

1. Click "Schedule an exam" on the home page, or "Schedule" in the left navigation.
2. Locate the card for your exam. Click on the "Click here to Activate" link to activate the eligibility. 
3. When the eligibility has been activated, click the "Schedule" link to open up the Pearson VUE scheduling page.
4. Proceed with scheduling in the Pearson VUE site.