ITC Reversal

Yes why not , you got the registration on 26/08/2018 & adding 30 days to it , it comes to 25/09/2018 , so you can file ITC 01 by 25/09/2018

Dear

As per Sub clause (b) Rule 40(1)

[b] the registered person shall within a period of thirty days from the date of his becoming eligible to avail the input tax credit under sub-section [1] of section 18 shall make a declaration, electronically, on the common portal in FORM GST ITC-01 to the effect that he is eligible to avail the input tax credit as aforesaid;

And Section 18 (1) CGST says :

1] Subject to such conditions and restrictions as may be prescribed-
[a] a person who has applied for registration under this Act within thirty days from the date on which he becomes liable to registration and has been granted such registration shall be entitled to take credit of input tax in respect of inputs held in stock and inputs contained in semi-finished or finished goods held in stock on the day immediately preceding the date from which he becomes liable to pay tax under the provisions of this Act;

Hope this might be enough for clarity in this regard

Note : Check the date you applied for registration must be before 17/08/2018