When does the clock start and stop?

As a participant begins a task, their timer will begin.  We log the time that elapses between when you first begin a task and when you complete it.  At the end of each task, you will be given the option to immediately start the next one, or you may take a break.  Participants do not accrue time between tasks. The winner is NOT who finishes the quest first.  The participant who completes the most main quest tasks (side quests do not count) with the lowest amount of cumulative time, wins.   Here is an example:

Tina joins a quest at 12:00pm.  She takes 5 minutes to browse the prizes screen and leaderboard.  At exactly 12:05, she starts Task 1 and receives her clue, which is a riddle.  It's hard for her to solve, as riddles tend to be, and it takes her until exactly 12:35pm to figure out and enter the correct answer.  Her total time recorded is 30 minutes, or 00:30:00.  Tina then has to go pick up her kids from school and run some errands, which take exactly 3 hours.  After that, she starts Task 2, which is a trivia question.  Tina doesn't know the answer, so she takes some time to scour the internet looking for the answer.  After 12 minutes and 12 seconds she finds it, and correctly enters the answer. Her new total time so far is 42 minutes and 12 seconds, represented as 00:42:12.  Over time, Tina finishes all the tasks the same day she started the quest in a total of 3 hours, 49 minutes, and 11 seconds, represented as 03:49:11.  That is her final time.