Eway Bill under Works Contract

We have got a Works Contract which comprises of Material Supply & Erection Service. The Invoice would be made in Per Sq Ft rate. The Site is in Chennai & Material to be supplied from Maharashtra in parts as project period is 6 months. 
So how would be d movement of goods n on which document. & Also the Invoice is to be raised by Assessee on his customer on approval of proportionate sq.ft.
Pls explain how Invoice to be raised & material to be shift & Eway bill implications.