GST registration

Kumar Gogia (49 Points)

02 August 2017  
dear expert sir
pls guide on one question

if GST registration applied 15/07 and GSTN received on 20/07 and on certificate it's mentioned valid from 20/07/17,
then purchase and sale between 01/07 to 20/07 is valid in GST or not
GST is added in purchase and sale bill was issue between that dates and GST charged.
is that valid or not?