Itc refund with claim in later month in gstr 3b

# 100% EXPORT UNIT

1. CLAIMED ITC WHICH REFLECTED IN GSTR2A AT THE TIME OF FILLING (AUG-NOV) TO SETUP IGST LIABLITY  LEFT BALANCE PAID BY CASH 
2. IN MARCH 2018 GSTR-3B - CLAIM ALL OTHER ITC IN GSTR3B WHICH RFLECTED IN GSTR2A AND NOT CLAIMED FOR SETUP IN POINT 1(FEW OF THEM FROM AUG-NOV AS WELL).
3. TILL DATE VARIOUS BILLS ARE NOT REFLECTED IN GSTR2A OR EVEN GSTR2 IS NOT OPEN
4. I HAVE CLAIM THOSE IN MAY 2018 GSTR-3B EVEN IF THEY ARE NOT REFLECTING AND GOVT IS NOT DECLARING DATE
5. LAST BUT IMPORTANT REGARDING REFUND OF ITC   “AS WE CLAIMED ALL OF THEM IN MARCH,  FEW MORE IN APRIL AND NOW IN MAY” IS THERE ANY ISSUE ?

PLEASE ADVISE.

THANKS