I clearly understand dispensations. Especially when there is clear scriptural evidence of a change in program. Israel was put aside but will be dealt with again. They were put aside right here in Matthew 23:
37 O Jerusalem, Jerusalem, the one who kills the prophets and stones those who are sent to her! How often I wanted to gather your children together, as a hen gathers her chicks under her wings, but you were not willing! 38 See! Your house is left to you desolate; 39 for I say to you, you shall see Me no more till you say, Blessed is He who comes in the name of the Lord!
That right there in red letters from Jesus Christ tells us at that point, Israel was set aside. Set aside until "Blessed is He who comes in the name of the Lord!" Not Acts 15 or sooner or later anywhere in Acts. Right there in Matthew's Gospel.
Im not so sure that means what you think it means.
Matthew 23:38 Behold, your house is left unto you desolate.
Jesus was talking there to the Pharisees who were being hypocrites in teaching to do what they didnt do themselves. Israel was not set aside at that point because it was later that Jesus said to go to the Jews first and not yet to the Gentiles.