plz help how to get itc in below mentioned case

Purchase 50k raw material in june 2018 and i got gst number on 6 june.... My CA is not showing that stock in gstr filing because i will not get itc.... But after i got gst number i have purchase approx 18k raw material which I will use in 50k raw material for getting finished product....... Than how CA will settle it and how I will get itc... How will he show output of 18k raw material which is purchased using gst number.