DAM - Setup of folders for backups

I'm realizing that my current system for cataloging/organizing is not going to cut it much longer and I'm trying to work out a plan that will work for the foreseeable and hopefully distant future to avoid having to change again!
I take mainly snapshots of familiy stuff, but have done a few paid shoots for friends as well and also have misc shots as I'm practicing my photography skills. Have approximately 4,000 images from not quite three years of digital photography.

In the DAM Book, he suggests filling one folder until it is the size of your backup medium, then backing it up and starting a new folder. Seems like a good idea, except I will likely be backing up (double) to DVDs (at least until we get an external HDD), which have a 4.7 GB capacity, and I only have about 9GB of photos *total* right now...which would mean I would have only two folders and two backups in the past three years?

How should I set up my folders so that I am backing up more frequently than every year and a half, lol? I am planning to rename all files beginning with date info, so it's not imperative that they are sub-sorted into specific date folders, although that seems to be the general consensus on how to set up folders (year/month/specific date folder hierarchy).

Thank you for your suggestions - I am eager to get this set up properly and start going forward organized!

I make my first backup by 100-frame folders as they come off the camera. If you don't fill the folders fast enough to get a DVD in a reasonable time (no more than a month), try doing periodic backups to CD, then when you've got 6 CDs worth, burn those directories to a DVD. If I haven't got enough new stuff when I do a backup, I also pull down some of the older files so all my backups have a certain amount of overlap.

I currently have a structure that goes

\year\month\original
\year\month\output
\year\month\working

If going forward I start to get to many files in a month I'll then add the additional day folder to the structure going forward easily.

I copy all new files into a folder called new. I then use DIM 2.0 to copy into the year\month\original folder. It also renames the files based on EXIF date and time and copies a duplicate to a second hard drive using the same directory structure. I then use Imatch to catalog everything.

Since I track everything by date range, I just file on a DVD and write the range on it.

What ever structure you follow DIM is pretty powerful and could help you re-do your naming and structure, plus it's freeware