I am by no means a speed reader, but usually I can read a book in one day's time. Here are a few tips on how to finish a book by bedtime!
First, make sure the book is approximately 200-300 pages. Trying to read lengthy books like War and Peace (approximately 1 billion pages) will be impossible. But a short easy to read book like Catcher in the Rye can be done in a day.
Get comfortable. Make sure you are sitting in a nice chair, and you have some tea or coffee. A comfortable, quiet environment makes you more motivated to continue reading.
Second, don't try to read the book in one sitting. You will surely get bored, your eyes will get tired and you may stop paying attention.
Read the book in time intervals. For example, eat breakfast, then read, take a shower, then read, jump on the train, read, you get the idea!
Speaking of the train, commuting is the absolute perfect time to read a book especially if it's a long commute! Read the book on the way to work, during your lunch break, and on the way home and the book can be easily finished!