Your first backup will always be the biggest.
If your first backup will be too big to get through the internet, we can send you a USB hard drive, which you can load your files onto, and return to us for loading onto the backup server, thus saving your internet bandwidth.
Please log a support ticket to get a hard drive sent out, and download the instructions of how to use from http://www.netrescue.co.nz/support/BrickLevelBackup.pdf