There are many ways that you can approach this one. In my experience though, the best way to get the most out of your practice exams is to use them at strategic points during your EIT exam preparation. When I was studying for the Engineer in Training exam, I purchased 2 different practice exams. I took the first exam prior to opening my Review manual to the first chapter. I definitely wasn’t prepared and pretty much bombed it, but looking back, know that this was necessary, as it established a baseline for what I needed to focus on.
At the end of my studies, a week before sitting for the exam, I took the same exact exam as I previously did to see what I had learned over the duration of my studies. This exam went much better, but was still a little sketchy and I struggled mightily on things such as time management and problem comprehension. This is expected though, so to hone in on my test taking skills, I waited a day or two and took the final practice exam, structuring it the most realistically as I could under timed conditions.
Using the practice exams throughout your studies will help focus your efforts on where you are lacking ability and comprehension. Structuring these exams as closely to what you would expect on test day will really help you polish up on your test management skills as well as give you that extra boost of confidence going in to exam day.
Check out the resource page for my recommendations for practice exams