Thank you for your question!
I stepped through setting up my schedule date (from the 'Register for Exam' menu) and found the discount there in the receipt displayed before submitting your chosen schedule location date. The exact step where your receipt and discount within the scheduling process is not mentioned by their instructions but this is where you will find it - stepping through scheduling and selecting your exam location and date, it will display your discount on receipt at the end step of that scheduling process.
All the best,
Cheers, From Fresno California
