ELigibility

Friends,

I'm qualified in 10th matric with 82% in 2003, following that I discontinued my 12th in 2005 on the family unfortunate. And I did my diploma in fisheries tech, worked for a software industry for an year. As I am vastly interested in auditing and economics, it made me to land here. When inquiring/surfing ICAI website and some institutes in Chennai on regard of eligibilty, I was told I'm not eligible with just a diploma certificate and I was asked to do +2. On this,I have two queries for now,

1.Is NIOS's senior secondary/ vocational certificate(equivalent to +2, which is the easiest way to get in) good enough to register for CPT and go beyond from there? 

2. As am already 24, I'm looking to register in ICAI on early next month, and taking up CPT exam on coming Dec 2011, gradually my 12th exams falls on Oct 2011. The question here is,  when should I produce my appearance/passed certificate to ICAI, between the time frame of these two exams? 

Expecting the clear mesaage from you.

Thanks