There are 40 questions in the test and you have an hour, so you have an average of 1.5 minutes per question. Therefore you should spend approximately 20 minutes on each section.
Why does it waste time if you read the text first and then answer the questions?
You will never have to read every word of any text to answer the questions. Your aim is to answer the questions, so you should practice scanning and skimming in order to locate the answers as quickly as possible.
If there are only 10 minutes left but I still have 10 questions to answer, what should I do?
You should continue answering the questions using the appropriate strategies, but if you really run out of time you should guess.