This will often depend on the reader's objective. If a students is reading a text for a class and the instructor has specific goals or specific ideas that they want to discuss with the class, beginning with questions or thoughts about the text in mind can be an effective approach. If reading begins with these questions, the reader can pick out or look for pieces of text that are particularly relevant or that provide answers to the questions they began with.
If, however, the reader is simply trying to enjoy a book, it may be more of a burden or less enjoyable to approach the book with certain questions and instead better to simply begin the text with an open mind and a desire to let the author work their magic in creating an interesting or exciting text. When the reader approaches a text with an open mind, they may be more likely to enjoy it or to find something new and interesting they wouldn't have noticed if they'd been reading the text with particular questions in mind.