Have not used, nor have knowledge of Nero labelling system. Have used labels two up such as you have.
The answer I found was to use a desk top publisher such as MS Publisher to draw out the correct size circles such as to fit the A4 label sheet and save this as a template. Then would make my own labels using this template.
It's a bit fiddly to set up initially, but does work. Would offer you the file but it comes out at about 15Mb.
Regards Brian j