Gst Return query GSTR–3, 3B

Example :-
The X Dealer Y releases the dealer in the bill 31 stamps and receives the bill Y after 4 days.
So he picks up this bill in his purchase book next month's date

X fills its GSTR 1 into bill 31 shows in it.
Y fills its GSTR 3B, does not show ITC's ITC

Want to know in what date this bill is to be spent?