Except the text does not say the called on the Lord...In fact Peter said to call on Yahweh..he was quoting the OT and did not yet talk about calling on Jesus
The first thing they said after Peter finished speaking was
Act 2:37 Now when they heard this they were cut to the heart, and said to Peter and the rest of the apostles, "Brothers, what shall we do?"
*it was only upon hearing ALL Peter said that they made this statement
*They were cut to the heart. Does that imply they had been free of a guilty conscious? No
*It was the fact that they were pained in the heart upon hearing all this that they asked what must they do
*If a person is saved, do the need to repent? If a Person is saved don't the already have the Holy Ghost? If they were already saved before asking this then Peter's response is off
If Peter was not talking about being saved then Luke is confused
Act 2:38 And Peter said to them, "Repent and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins, and you will receive the gift of the Holy Spirit.
Act 2:39 For the promise is for you and for your children and for all who are far off, everyone whom the Lord our God calls to himself."
Act 2:40 And with many other words he bore witness and continued to exhort them, saying,
"Save yourselves from this crooked generation."
Given that it's hard to see where you get they were saved during Peter's speech, before he finished