When to register for servise tax?

Hi Friend,

I am starting a new business of tours and travels, and the type of business Sole proprietorship. please guide me for my below mentioned query:

1. when should i register for servise tax? is it before i start first transaction of my new business or after i reach taxable income of 10 lacks?
2. If the answer is later one, then should i continue business without servise tax number till it reaches 10 lack?
3. In this case the INVOICE to be generated will be without Service Tax Number?
4. Foe the sole proprietorship business, do i need to have PAN card  of business entity or i can use my own PAN card?

Thank you

Alpesh