Technically 2nd method should be applied, but mostly the 1st method adopted by the majority... actually there are certain prescribed date for the particular percentage of tax to be deposited... i think 30-40% by 30th sept 60% by 31st dec & 100% by 31st march... 1st & 2nd installment will be under advance tax & last one under self assessment...
percentage can be different.... BTW i am not a professional accountant... I am a software developer by profession... above information are based on our clients software development studies....
personally I do not file my return by 31st july'12, me & my tax return filer friend both are very lazy... mostly my returns are NIL / nominal refund tax return as my TDS are already covers my tax liability....
As far as my share trading income is concerned that is always in a big loss since 2008... my friend suggested me to claim the losses by carry forward it... to adjust by profits in future, but I didnt, bcz I know that I will never be in profit to adjust these losses....