Yes you can claim ITC on Invoice, Debit Note pertaining to FY 2018-19 till the due date of filing GSTR-3B Return for the month of September 2019. The Due Date to file GSTR-3B for the month of September 2019 is 31.10.2019.
Hence the last date to avail ITC is 31.10.2019.
Refer Provision of Section 16(4) of the CGST Act 2017.