caleb condit , May 29, 2006; 03:05 p.m.
Since this is the first one made at this size, it's number one, or an AP (artists print). IF you plan to print more at this size, make it 1/20. If not AP.
But this whole thing of numbering comes from the history of traditional printmaking where an artist makes a certain amount. It was considered that when an artist makes 20 vs 200 prints there is more care put into the 20 and they are also lower in supply.
I think you should label this one 1/(however many you plan printing), and call it a day. The other sizes you gave as gifts would be AP, and this will be a limited edition at this size.