Why did you say that the September 1948 declaration was late?
Because it came four months after the Israeli one, which staked-out a claim to a piece of Old Palestine.
Had the Palestinians had the brains to declare on the same day the Israelis did (the day that the Mandate ended), their position would have been stronger.
Think of it as a Gold Rush.
You have 100 acres of land on which gold is believed to exist in large quantity.
You have two gold prospectors competing.
Somebody suggests that they divide it up.
Prospector A says "OK", and files a claim for his half.
Prospector B says "No, I want the whole thing", and doesn't bother to file.
A and B start to feuding, and B gets the worst of it, and loses some of his half in the process.
Four months later, B goes to the claims office, and tries to file a claim for the whole thing.
B gets laughed out of the claims office.
When the outside world gets wind of it, most of the Territory is laughing at B, as well.
As more time passes, and A continues to encroach on troublesome B, and B continues to start fresh firefights, B continues to get the worst of it, time after time after time.
B never learns.
Worse, B continues to press his claim for his old half, and wants a piece of A's original turf, as well - actually, B continues to insist that it's still all his, even though the world has long-since abandoned any pretense that B's claim to take it all is valid or operative.
B is, by then, not only viewed as a laughing-stock, but as the village idiot.
And it all started with B not having the brains to file his claim the same day that A did, way-back-when.
That's why I say that the September 1948 declaration was late.