The book of Acts is a brief history of how the church came into being. The book of Acts contains very little doctrine.
A person is covered by the blood of Christ at the moment they receive Him by faith. Baptism has nothing to do with salvation or participating in the life of Christ.
Romans 2:26-29
26 If therefore the uncircumcised man keeps the requirements of the Law, will not his uncircumcision be regarded as circumcision? 27 And will not he who is physically uncircumcised, if he keeps the Law, will he not judge you who though having the letter of the Law and circumcision are a transgressor of the Law? 28 For he is not a Jew who is one outwardly; neither is circumcision that which is outward in the flesh. 29 But he is a Jew who is one inwardly; and circumcision is that which is of the heart, by the Spirit, not by the letter; and his praise is not from men, but from God.
NAS
When someone is baptised they are being obedient to the Lord, but the act of being baptised does not seal us or regenerate us; we are sealed and regenerated by the Holy Spirit.