When it comes to saving for retirement, timing does matter. In the example above, Jill started putting away $100 per month at age 30 for the next 10 years and then stopped. Jack contributed the same amount to his retirement plan every month starting at age 45 until he was ready to retire at age 65.
So, if Jack contributed more to his plan over a longer period of time, why did Jill end up with a larger balance when it came time to retire? Compounding interest. Because Jill started saving earlier, her account balance had more time to earn interest on its interest, and she therefore ended up with the largest nest egg. Sorry, Jack.