Consider managing your time by ignoring time all together. You might find yourself more efficient and find out that the clock is really your enemy. Here's why.
I recently noticed a problem when managing my own time: when I'm reminded of how much time I have to accomplish a particular task (or set of tasks), it tends to to take me a lot longer. This isn't just lost seconds due to checking the time, but that when I check the time I start making estimates of how long it'll take me to finish something.
Here's an example: I give myself 45 minutes in the morning to get ready. It takes me about 20 minutes to shower, brush my teeth and get dressed. It also takes me about 15 minutes to make and pack a lunch and pack for work. That leaves me 10 minutes of flex time. Periodically during the morning routine, I check the clock to find out how I'm doing. Sometimes I'm ahead by a few minutes and that makes me think I have extra time to try and accomplish even more. Usually I'm right and I can fit in an extra email or something equally quick, but if there's still extra time on the clock I'll keep using it until I can't. In the end, I'm rushing out the door or even leaving a few minutes late.
The Solution: Stop looking at the clock. Stop checking the time. Being ignorant of the time has helped keep me on task. I've found I get done with everything faster and can either leave a bit early or make use of that added flex time until I have to leave without worrying about rushing out the door. While you can't always ignore the clock, reducing the number of times you check it may help keep you on task.