Sorry to make you more confused.
First of all I don't use NSE NOW, I use Odien Diet.
I place a buy order with type Margin. Once this is executed, I can sell it the next moment. If I sell the same scrip and same quantity, it is considered as squared off and Intraday trade. If I don't square it up, it is automatically converted to Delivery trade.
If it does get converted to Delivery trade, I can sell it the next day (T+1) even though the exchange time to show the scrip in your portfolio is T+2.
I am not 100% sure here - In your case as well, when you put buy order with type CNC, you should be able to sell the same scrip the next moment after execution. Only make sure when you put sell order, the type is Delivery. If there is an error saying you do not have the scrip / quantity then you should be able to sell it the next day.