Starting from September 1, 2020, upfront margins are required for all trades according to this SEBI circular and guidelines from exchanges. This has the following consequences. 

Sales proceeds from investments can be used for taking new positions
You can utilize 80% of the sales proceeds from your investments as soon as you exit them to enter new positions (other stocks or F&O positions). 

Based on the new peak margin regime, there’s a cap on maximum intraday leverages and only 80% of the credit from selling your investments will be available for fresh trades. The whole credit will be available from T+1 day. 

NOTE: If you sell your investments and then purchase them back after using the sales proceeds for other trades, a margin penalty will be charged as per the new peak margin regulations. 

Using the sales proceeds from T1 investments
Like your stock investments, you can sell the T1 investments, i.e., stocks purchased on the previous day which are yet to be credited to your demat, and utilize 80% of the sell value of the proceeds to buy fresh stocks for delivery. Although, you will be only able to use 60% of the sell value for F&O. 

Intraday profits can be utilized for fresh positions but only after they are settled. Your Neo fund balance will show your intraday profits only after they are settled by the exchange. The settlement of funds takes places after 2 trading days for equity and after one day for F&O. 

If the T+2 day for equity and T+1 day for F&O happens to be a settlement holiday, then the intraday profits will be available on the next trading day. 

Option sell credit can be only utilized to purchase options on the same trading day
While exiting your long/buy option positions or entering new write/short options, the proceeds of option premium can be utilized for only fresh long/buy option trades on the same trading day and only in the same segment. For example, you will be unable to use proceeds from equity options for currency on the same of day transaction. However, these proceeds can be used for all other types of trades from the next trading day.