For timing you're leaving cert maths exam, the best advice is to allow some time for the beginning and the end. Then divide the rest among the questions that you have to complete. It is not the best way to manage your time.
Before you go to Ireland leaving certificate examination, there are certain questions that you know you can do well. These are the ones that you've practiced so many times that you know what to expect. You'll probably have gotten used to looking at old papers, and you will be able to quickly evaluate a question – at most as far as parts a and b. These questions will be easy to scan and quickly choose.
Instead of spending too much time choosing your questions at the beginning, pick your top ones quickly and take a quick glance at the last ones. Notice the weakest ones, the ones that you aren't sure about but don't worry.
You can practice scanning on old paper and then time yourself to see how fast you can pick your top four and mark any remaining ones. Do not wait until the day of your exam to practice scanning. It is an essential part of exam preparation.
It should take you no more than five minutes to complete the task. The faster you can do it, the better. This gives you time to think about the best answers to your worst questions. Start working immediately on the best ones. This will help calm your nerves and get you warm. After you've finished the positive ones, take the time to look at the less important questions. Time losses are not allowed by a high grade in leaving cert mathematics. That's why try to manage your time.