The previous Lubavitcher Rebbe, Rabbi Yosef Yitzchak Schneersohn related the following about the time that is referred to as the “heel of Moshiach.”
One clearly sees that although a hat that is too small is not unbearable to wear, a shoe that is too small crushes the feet—becoming insufferable.
It is therefore understood, that the Almighty need not be to exacting in regards to the time of the heel.
 Otzar Pisgamei Chabad. Vol. 1. Pg. 407