How would the book have been different if it had taken place in a different time or place? The book needed to jump back in forth in time, because that was what the book was centered around. Wouldn't have been as good, if the places and events were different.
Make a list of facts you learned from the story. Boys could only go forward and girls could only travel back. Charlie's aunt and dad were travellers, as well. Billy was adopted by Ben Franlkin and his name become William. Dancer was a boxer. Tocks were machines.
List the characters and describe them. Charlie was about 15. Tall and thin. He was from London. Yvaine was a young girl with a baby named Billy. She was a thief. Charlie, Yvaine, Sophie and Charlie’s dad are all time travellers. Tick Tocks are mechanical killing machines. I learned where Ben Franklin's son came from.
If your book was a mystery, tell what the mystery was and how it was solved. It wasn't really a mystery. More just plain fiction.
Disclosure: I received a review copy of this book from the author.