Prufrock has led a pretty unfulfilling life, to say the least. He wants to lead a heroic life, but in reality, he's much too nervous, shy, and neurotic to do so. Each time he ventures out into society, he is reminded of his many shortcomings as an individual.
Far from leading an exciting, rich, fulfilling life, Prufrock is forced to acknowledge the uncomfortable fact that so much of his existence has been frittered away in pointless social gatherings at which, one presumes, coffee was invariably served. Hence the reference to measuring out his life with coffee spoons.
The measure of Prufrock's life has not been heroic deeds or passionate love affairs but by an endless round of painful encounters with members of the opposite sex in respectable social gatherings. Looking back upon the life that he's lived, Prufrock can only lament how it's all turned out.
This is not a heroic age, and Prufrock is certainly no hero. He is marking time and nothing more, and he can only do by the countless coffee spoons he's used in an ultimately forlorn attempt to make his mark upon a world that he neither likes nor understands—and which is a constant source of fear and disappointment.