Best practice is to answer as the tale is playing. Read the questions when they give you time to do so so that you know what to be looking for in the recording and then answer the questions.
Tip - they usually go in order so if you missed one, just forget it and keep going otherwise you'll get more wrong gin trying to 'fix' the one you missed.
If you haven't done so yet, I would highly recommend running though a few practice exams so you become familiar with the format. Taking the IELTS isn't just about your English ability. As with other standardized tests, your test taking ability with their specific format is also tested