It didn’t become Roman Palestine until the second century AD.
Yup, the name was changed after the Romans quelled the Bar Kokhba revolt in 135 AD.
135 to be exact, when the Emperor Hadrian declared the Roman Province Judea (and Samaria) to be Syriana Palestina, or part of the Syrian Province of the Roman Empire. Hadrian also named Jerusalem Aelia Capitolina, which retained that name until captured by the Muslims in 638. Hadrian had suppressed the Bar Kochba Rebellion in 135 and sought to erase the memory of Jewish ownership of Israel and Jerusalem. The Historian Eusebius wrote of ‘Palestine’ in 300 and the Catholic Church, which was technically solidified in 326 by Constantine, adopted the term in its teachings. Hadrian’s method of renaming Israel is still in place to this day, as the British adopted the name when it authored the British Mandate of Palestine in 1922 at the League of Nations, and was adopted by the UN as well. All of this was to erase the existence of Jewish Israel. That was true in 135, 1922 and to this day. There has never been a nation of Palestine, but part of the Roman Province of Syriana Palestina.