I’m an adult student. Started at 33 - just turned 38. Practicing 3-4 hours daily. Don’t get this book. Take music theory classes, learn harmony, and get an excellent teacher. Mine is from the Russian school and changed the way I approach the instrument. Also - you can become a good pianist if you start as an adult. You just won’t be attending Julliard as an instrumentalist. But who cares? Neither did Beethoven. My #1 advice: practice in perfect time. Build a natural sense of pulse. The dirty secret is it’s easier to play a piece in time than the converse, especially at high velocity.