I recently had a potential BJCP Tasting Exam candidate who was not able to take the exam because they had not yet passed the Web-based Beer Judge Entrance Exam. They waited until the last-minute and then decided to take it thinking it was not going to be challenging. While the entrance exam is not going to tax an experienced judge and homebrewer, it will prove problematic to those who are new to judging and brewing. One other examinee admitted they did not pass the first time they took the Entrance Exam and so they boned up and took it again.
My suggestion for anyone is to study. The BJCP has a study guide available online which will help in preparing for the entrance exam and the Written Proficiency Exam. Whatever you do, do not assume that because the topic is beer and homebrewing the exam will be a cake walk. It is not, even the Tasting Exam will tax your senses and abilities. So it you are one of those planning to take the exam in the near future, study and prepare and you will do well.