Let say I would like to run social networking with specific niche group. Let also say that group are people in marketing professional. Just for example.

How much time do you think we need to get first 1000 and first 5000 registered users? Again, it is specific niche market within social networking.

In promotion team are going to be 2 persons and they will promote network in follows way:

-blogging

-press release

-forums

-replies to articles with our signature

-link exchange

Do you think is possible with only that methods reach from 100 to 1000 in 1 month and from 1000 to 5000 in extra 3 months?

If you are planning to sell it within 6 month, you can't. Do something else; don't start the project. You need atleast 2 years to get that target.

But you may try other ways to promote your site to achive your target in less time period

-> TV, radio, newspapers.

I am absolutely don't trying to sell it within 6 months, maybe years. I am going to set up company in UK only for that project because my goals for that project are quite high.

You mean I need 2 years to get 5.000 users?

About TV, radio and newspapers you thought probably about PR, not ads right?

I am talking about ads. If you want fast result then you have to spend lot of money.