I have my h1b approved and now am legally allowed to work after October 1st 2007. I also received my itin. I will have to apply for my social security number soon. When is the best time to apply? Do I need to take a copy of my itin as well?

There is no "best" time to apply for a SSN.

Once you have the H-1B approval, you have justification to apply. Do it as soon as possible so you will receive it and have it applied to all of your payroll records well before the end of the year to avoid confusion.

Hi! I had gone to the SSA ofice this morning to apply for a SSN. My application was again not accepted though I had my Passport, Drivers License and I797 approval with me. I was told that in my passport, I94 has a stamping for H4 and I can only apply if I get another I94 on the passport with H1 written on it. No matter what, I was told that their system will not accept my application before October 1st. What do I do now? Please guide.

Apparently you will need to wait until you actually get the H-1B visa before you can apply for the SSN.

Until then, just use the ITIN.