A man can complete a job in 40 days working 6 hours a day. He started the work and on the second day, another person who can complete the job in half the time as the first person joined him. On the third day, a person who can complete the job thrice as fast as the first person joined them. This process continues till the entire work is completed. After how many days from the start will the work be completed (Every day consists of 8 hours of work)?