Catholic families need priests: to baptise their children, to provide Mass, to teach the faith (and enable catechists to do so). Priests come from families and good Catholic families are well-placed to provide the environment where a vocation from God can be listened to and followed. Plenty of priests come from non-Catholic or non-practising families but parents who love their Catholic faith often say how delighted they would be if one of their sons were to become a priest.
We should remember that God will not let us down, as Pope John Paul II said:
The synod, with complete trust in the promise of Christ who has said: 'Lo, I am with you always, to the close of the age' (Mt. 28:20), and aware of the constant activity of the Holy Spirit in the Church, firmly believes that there will never be a complete lack of sacred ministers in the Church.... Even though in a number of regions there is a scarcity of clergy, the action of the Father, who raises up vocations, will nonetheless always be at work in the Church. (Pastores Dabo Vobis n.1)The Priestly and married vocations are complementary: the Church in general needs families and priests individually need to be in close touch with families to have a proper awareness of the daily joys and struggles that they face, and what they most need from the priest, namely holiness and sound teaching. A wise priest once advised families always to ask the blessing of a priest who visits their home. This brings grace to the home since the blessing is given as a sacramental of the Church. It also reminds the priest of his place in the family home and, if necessary, reminds him of his specifically priestly identity. To quote Pope John Paul again:
The more the laity's own sense of vocation is deepened, the more what is proper to the priest stands out. (PDV n.3)It is important to remember that the second Vatican Council spoke of the lay apostolate, which is specific to the lay state, not lay ministry, which is often a matter of assisting at ecclesiastical functions. The family, the domestic Church, is a privileged part of the lay apostolate.
In practical terms, if a boy begins to show signs of a vocation, or indeed any signs of a deepening spiritual life, it is important for his parents to encourage him gently in this. Fathers can do so very much in this regard by their example, and it is sad that the task is often left to mothers alone.
Later, if a young man expresses an interest in applying for the priesthood, he should be encouraged to go to Mass daily if possible, to attend Benediction or other devotions in the parish, and to serve at the altar, perhaps assisting in the training of younger servers.
It is wise to allow him some privacy and to understand that he will wish to spend time on his own in prayer at home. At this stage, obviously, it is important for him to to talk things through with a good priest: one who is prayerful, doctrinally orthodox, and happy in his priesthood.
The process of discerning a vocation is a long one and continues all the way through the seminary until the Bishop's call to ordination. We need to remain open to the will of God, whether it is for him to be a priest or to understand that his vocation lies elsewhere. If he has sincerely tested his vocation, there should never be any hint of "failure" if he comes to the conclusion that he should not continue training.
As I said, these are just a few notes and I expect that some readers will have other ideas and suggestions. Don't forget that we must pray for vocations and that Eucharistic Adoration is especially powerful in this regard.