You can see the declination here, when πολύς is an adjective:

http://11dim-evosm.thess.sch.gr/online/glossa/orthpoly/

As adverb the word πολύ is not declined.

Επειδή θα ήταν στα αγγλικά "I don't have enough time".
enough = αρκετό
much = πολύ