An updated notification sent by Pyongyang to UN agencies today -- a copy of which was released by the South Korean government -- said the launch would now take place between February 7-14.
The initial window announced by the North on Tuesday had been February 8-25.
The planned launch has been condemned by the international community as a disguised ballistic missile test that amounts to another serious violation of UN resolution, following the North's nuclear test last month.
The North insists its space programme is purely scientific in nature, but the United States and allies, including South Korea, say its rocket launches are aimed at developing an inter-continental ballistic missile capable of striking the US mainland.
UN sanctions prohibit North Korea from any launch using ballistic missile technology.