Technically there is no documented ordering to the import of your images. As such, folks often get in trouble when attempting to use the "import sequence number" when they really should use the camera's "original file number".
The import dialog as a sort option at the bottom of the dialog. By default it is set to either timestamp or filename, which should be the same thing for most cameras. However, this is not guaranteed to be the order of import, just order of viewing.
The Library grid also has a sort option at the bottom of the screen for ordered viewing.