Answering the first 10-15 gets you on higher ground...it does not guarantee anything. if you answer back to back questions wrong in a series consistently ...your performance on the first 10-15 questions wont matter that much.
I would stand by the argument that the first 10-15 questions contribute more to your score than the remaining questions.
The bad thing to do is.... if you spend most of your time on the first 10-15, it will leave you with less time at the end. So you will have to randomly guess on the last 6 or 7. that reduces your score.