The exam paper recommends that you spend about 40 minutes on this question and this is about right. Remember that Task 2 gives more to your final writing band and so you should make sure that you have enough time after Task 1 to properly answer Task 2. Some students do Task 2 first in order to make sure that Task 2 is answered well before they get onto Task 1. There is no problem with this but make sure you write the 150 words to give a good answer for Task 1 as well.
    So, whatever you decide to do about your approach to Task 1 and Task 2 in the writing paper, make sure that you spend approximately 20 minutes on Task 1 and 40 minutes on Task 2. This should give you the right amount of time to provide good answers to both tasks.