The “Nakba” didn’t begin in 1948.
The “Nakba” - a term originally coined by Constantin Zureiq to describe the “catastrophe” of 7 Arab armies failing to “erase Zionism”, didn’t begin with the official Arab invasion into the land of Israel on May 1948.
It began on November 30th 1947 - one day after the United Nations voted on the partition plan for creating a Jewish state on Jewish majority owned land, and an Arab state on Arab majority owned land. A solution that would have required no one to leave their homes.
Instead of accepting the plan and establishing an Arab state, the Palestinian Arab leadership Initiated a war - beginning with the Fajja bus attacks on November 30th 1947, the attacks on Mamilla shopping center on December 2nd 1947, the attack on Kibbutz Efal on December 4th, and the large scale attack of the “Holy Jihad Army” on Hatikvah Neighborhood in Tel-Aviv on December 8th 1947.
The road to Jerusalem was blocked in an attempt to starve over 100,000 Jewish residents there. And although the neighboring Arab states declared they will not enter until May 1948 (when the British would leave). However, they established the “Arab Liberation Army” which invaded on February 1948, Egypt sent in the Muslim brotherhood “volunteers” to attack Kfar Darom, and Jordanian Arab Legion attacked Gush Etzion both on April 1948.
So no, “it” didn’t begin in May 1948.