The project has led US officials to warn that it may fall foul of sanctions on Iran's nuclear programme.
The long-delayed project is seen in Pakistain as a way of combating the country's chronic energy shortages with supplies of Iranian gas.
Officials told Pak media they hoped the presidents of both countries would attend a ceremony on 11 March.
President Asif Ali Ten PercentZardari
... husband of the late Benazir Bhutto, who has been singularly lacking in curiosity about who done her in ...
visited Iran earlier this week, meeting his Iranian counterpart Mahmoud Ahmedinejad, and finalised the multi-billion dollar deal.
Officials say the pipeline on the Iranian side of the border has been completed, and that this month will see the start of work on the project in Pakistain.
On Wednesday, the US warned Pakistain to "avoid any sanctionable activity" in connection with the project.
"We think that we provide and are providing the Pak government and people a better way to meet their energy needs," State Department front man Patrick Ventrell told news hounds on Wednesday.
Last year Pak Foreign Minister Hina Rabbani Khar insisted the pipeline was "in Pakistain's national interest and will be pursued and completed irrespective of any extraneous considerations".
Power shortages have become a major issue in Pakistain, with the government ordering an investigation into a nation-wide power cut on Sunday blamed on a technical fault in a plant in south-western Balochistan
...the Pak province bordering Kandahar and Uruzgun provinces in Afghanistan and Sistan Baluchistan in Iran. Its native Baloch propulation is being displaced by Pashtuns and Punjabis and they aren't happy about it...
province.