There are many benefits to being on schedule.

Maybe you’re not the best programmer, the best systems architect, or the smartest person in the room. If you’re a person who can be relied on to stay on schedule, you will still be extremely valuable to people. Sticking to a schedule is a very rare thing in business. If you can pull it off, you’ll have a very rare and valuable trait, indeed.
Punctuality makes you appear more reliable to other people. Obviously, you can’t end on time if you don’t start on time. Take the initiative to be the person who always starts on time.
“80 percent of success is just showing up.” — Woody Allen.
Really, you would be amazed at how much you can help things just by being there. The person who habitually comes to work late? Unreliable. The person who multitasks during meetings? Unfocused. The person who skips meetings because he’s too good for them? Disengaged.
Being there is also key to being lucky. See, luck is simply preparation meets opportunity. You don’t get opportunities if you’re not there.
You can’t succeed without starting. Don’t be afraid to tackle the big projects. Often just getting a big project started is the hardest part.