@ Zerodha,
exactly, it makes no difference if you consider the first day or not unless that first day of writing overlapped with the last day of the challenge. Just consider the expiry day if the position is not closed.
I don't wish to push it hard, all I'm saying is within the challenge period and post expiry those sold options have no meaning and as far as I understand it is considered as profit.
Let us not deal with day-1 and day-n to confuse all the way more. As per what I'd understand from your rules, on the 60th day close, you should be profitable. it doesn't matter if you loose 10k in 5 days and make 14k in remaining 55 trading days. the equation would be initial capital -10k + 14k = profit +4K, eligible for the brokerage refund, isn't it?
So if your challenge started on 15/2 and say I had a sufficient balance "X" to sell the below options on 16/2 on overnight basis.
on 16/2 suppose these were my trades all with single nifty lot to keep it simple:
sold 1 lot 4500PE-Feb12 @ 50 to expiry worthless on expiry 23/2
sold 1 lot 5700CE-Mar12 @ 80 to expire worthless on expiry 29/3
sold 1 lot 4200PE-Apr12 @ 120 to expire worthless on expiry 26/4
post 23/2 close, my balance capital would have been X + 50*50 = X+2500
post 29/3 close, my balance capital would be X + 2500 + 80*50 = X+6500
post 26/4 close, my balance capital would be X+6500 + 120*50 = X+12500
Now say, I also had sold 1 lot 6000CE-May12 @ 80 say, on 7/3 and let it expire. this may not get considered as May expiry is on 31st and your challenge closes somewhere before that. so all the contracts of May expiry may not get considered. OR you can consider them day-wise
Hope I'm making sense.