Nopes! it should be read as data of 18th only. I picked up the data very late in night, but normally by 8 PM everyday information from all the exchanges reach SEBI, and then you can see the same day data.
Opt.tra. in his post earlier in this thread has mentioned that the OI data changes
fast during the intraday within minutes and that changes the whole game,IMO we should be able to monitor that data too so that we can decide timely on exit and entry of our positions.