I wrote in my book that the little act isn't discernment yet.
It is true that it isn't. However visiting St. Ignatius present writers today put the idea that the Spiritual Exercises is foremost for freeing oneself from attachments.
The Blessed Virgin Mary's question was for freeing us from our attachment to sex. Yet it isn't saying so since it points to avoiding all evil. It focuses rather on the living part where the will is strengthened to do good, a gift of virtue to doing good things becoming natural according to St. Thomas Aquinas.
The vastness of goodness makes us uneasy to choose what good acts to do. The problem is one's present capacity; one cannot receive what one does not have. Being a repentant hardened sinner, we don't have anything but wait for the mercy of God. The genius of the Blessed Virgin Mary's question is it taps on our natural giftedness, a witness to God's creation that everything is good. "What good can you easily do here and now? Do it." It starts goodness in whatever form is left in the repentant hardened sinner. There is where the act of choosing goodness starts. When some degree of perfection has been accomplished, his state of soul wants for more goodness, to be perfect as his/her Heavenly Father is perfect. And where there are two or more pronounced choices becoming a dilemma, one can start the act of discernment.
When not to discern? When after all the wanting to make decisions, no two or more choices becomes pronounced, by repeatedly testing the Spirit in each different and many choices. This is where continuing to do the little acts, doing the existing present duty for example, is the answer, and one should stop discerning fruitlessly. Detachment may be needed and the question of BVM accomplishes such need, not mentioning that it also continues to actuate goodness.
Hail Mary, full of grace...