Today I had to make a timer in After Effects that automatically counted up in milliseconds starting from the time it was placed in to the timeline. I also needed it to freeze on the 60 seconds mark. With a bit of searching the web as well as the help of expert Programmer "Mambose" we managed to come up with a simple expression that executes the task perfectly. In addition to that, you can easily adjust the text that displays at any specified time (I've underlined those editable areas, for this video I made it stop at 30 seconds).
The code can be found on my website here: retouchcanada.com/after-effects-timer-expression/
I hope you enjoy!