If you miss to take credit in f.y. 2019-20 , you can claim ITC of f.y 19-20 up to September month GSTR 3B return date of year 2020 subject to you are having valid purchase Tax invoices.
Yes, you can take ITC as per sec 16(4) ITC can be avail till September gstr3b of succeeding year(In your case Sept. 20)or date of annual returns whichever is earlier