GMAT is an adaptive test and keeps adjusting the difficulty level of questions based on your performance. Since the first few questions on GMAT are in the Medium Level of difficulty. making mistakes here tells the GMAT algorithm that you are below average. Hence the GMAT adapts downward very quickly. Clearly, you will have to make a greater effort to take it to a higher level from here on
Therefore, the first 10 questions on each section of the GMAT have what can be called a 'hygiene factor effect' i.e. if you do badly on these, they will affect your section score adversely, but beyond a point at which you do well enough on these, they are unlikely to ensure a high final score just because of this fact.
In other words, merely cracking the first 10 questions on GMAT won't automatically ensure a high score in that section. You will have to prove your competence right till the end of the section.