What Poland could do with two weeks of warning

What could Poland do with two weeks of reliable warning before the German invasion?

Mobilise reserves, prepare demolitions and traps around infrastructure, and monitor likely fifth-column groups.

The answer begins with reserve mobilisation, using the warning period to bring trained personnel into their wartime formations. Polish forces could also prepare traps and demolition charges around infrastructure likely to be seized or used by the invader. Quiet surveillance of suspected fifth-column groups would help protect mobilisation and communications from internal disruption. The value of warning therefore lies in converting time into manpower, denial plans, and counter-subversion rather than waiting for the border attack itself.