The answer would be 0 - in 1939
Nope. We were still putting up a decent defense; less effective than it could be - that's true - because the c*nts attacked us from West, North and South and we were spread along the borders, so it was one huge encirclement battle from the very beginning. Still, Wehrmacht was starting to experience logistical problems, there were counter attacks in progress (including the Battle of Bzura) and a lot of untouched units were marching towards Przedmoście Rumuńskie, to form a new defensive line there...
pl.wikipedia.org/wiki/Przedmo%C5%9Bcie_rumu%C5%84skie
... unfortunately, we were stabbed in the back by the Soviets, who entered from the East on the entire length of our eastern border (about 1400 km) - 620,000 soldiers, 4700 tanks, 300 planes. And in the east there were only rare KOP (border guards) units. That sealed our faith. But still, I wouldn't say that the chances were 0.
As for 1944... a complicated issue. With hindsight, a mistake.