Is there a "session timer" macro?

We're trying to come up with an easy way to track time on workorders. If I could open an existing file or start a new file then hit a macro to start recording time then hit stop when it's ready for proofing I can add the time to the workorder form for more accurate pricing. Seems our company is losing a lot of money because of the time spent fixing customers layouts. You can lose a lot of customers trying to explain why their files are no good. It's become common practice to redraw or touch up the designs. if there were some way to do a simple time stamp. I know there are lots of timers out there and I've tried some but they all take too much time to even get them to start i.e. find your project start/edit time blah blah. All I need is start stop function.