How could Booker regulate his work routine ?

I'm not sure what part of the story you are referring to but I found this quote from the text:

There was a large clock in a little office in the furnace. This clock, of course, all the hundred or more workmen depended upon to regulate their hours of beginning and ending the day’s work. I got the idea that the way for me to reach school on time was to move the clock hands from half-past eight up to the nine o’clock mark. This I found myself doing morning after morning, till the furnace “boss” discovered that something was wrong, and locked the clock in a case. I did not mean to inconvenience anybody. I simply meant to reach that schoolhouse in time.