The Jews are among the nations, being scattered .
Acts 2
¶And there were dwelling at Jerusalem Jews, devout men, out of every nation under heaven.
Acts 11
19¶Now they which were scattered abroad upon the persecution that arose about Stephen travelled as far as Phenice, and Cyprus, and Antioch, preaching the word to none but unto the Jews only.
In Luke the term isn’t limited to Jews only. So, I still believe the Apostles knew that the Gentiles would receive the promise. If they didn’t then their minds were not opened to understand as Luke 24 says. That doesn’t mean that there wasn’t an order to things and it wasn’t yet time to take the gospel to the Gentiles.