Probably in a similar way as is still practiced in the Eastern Rites: that is, it was the second half of baptism, and was administered immediately following baptism. A vestige of this survives in the Latin Rite, where there is still an anointing with Sacred Chrism immediately after Baptism. So it would have been the anointing at the end of the initiation ceremony when the Apostles administered Confirmation.
The 12 Apostles on the Day of Pentecost.
during the time of the Apostles but no exact time
Because the apostles did it, (Acts 8.17)
When the Apostles received the Holy Spirit on the Day of Pentecost.
No, a deacon administers the sacrament of Baptism. Deacons can reside over a Marriage Ceremony as the official 'Witness'. This is because only two lay people can administer the sacrament of Marriage.
The 12 Apostles receiving the Holy Spirit on the Day of Pentecost.
The Day of Pentecost, in the Acts of the Apostles.
Because the Sacrament of Confirmation is a young person's commitment to the Holy Faith. It is far more important for the bishop rather than the priest to administer this Sacrament. The only other Sacrament where it is the role of the Bishop to administer is that of 'Holy Orders,' which ordains men into the priesthood.
Because the apostles did it, (Acts 8.17)
Christ initiated what is now known as "confirmation". Confirmation began the day of Pentecost when Christ sent the Holy Spirit to be with the Apostles. Christ had already ascended into heaven. He sent the Holy Spirit to give the Apostles courage to spread the Word of God. It is through the indwelling of Spirit that we mature in our spiritual relationship with God.
Because a Bishop has the fullness of the priesthood of Christ, he, alone, can administer all the sacraments, and is empowered by the Holy Spirit to complete baptism with confirmation.
Because Christ Promised to send to His Apostles and to his disciples the Holy Spirit.