For GSTR 1 return we can file on or before 30th Jun-2020 without late fee... Bcoz, the late fee is waived as per notification no 33/2020 CT date: 03/04/2020
For GSTR 3B the date extended based on Turn Over of PY...
What is Your turn over in preceding year...?
Please refer notification no 32/2020 CT date: 03/04/2020