Modern Vespa

are there any early signs to look for that the brakes on my 2001 vespa et2 are getting very low and need to be replaced before its too late...thanks

You can either check visually how much of the pad material is left (easier on the front) or wait until you start hearing a metal on metal grinding noise when you brake heavily. This will get progressively louder and more frequent the longer you ignore it.

You will see the shoes when you replace the rear tire. You can look down and see how much material is on the front pads pretty easily.
If it's an ET2 with typical US miles, there's likely not a lot of wear on the shoes.