My first find was a Multi Cache near my home coords on 2011-04-16.
Round about half an year before I took a sunday walk around and on one of my standard pathes that time. When I came along a side street I saw in some distance a group of persons (of any age as I discovered on coming near to them) rounding a substation ever and ever. When I passed them, some of them asked me, if I had hidden there something. On my astonishment they explained what they were doing there and summarized it as "geocaching".
In the following winter time I did some researches about this geocaching and found it interesting. On a sunny, but cold April day, the 16th I decided to try my first cache. I printed out the description, starting on the wrong side of the track. Thus several times I crossed my path with another geocacher doing the same cache. Finally we decided to finish this tour together.
After this adventure, which hooked me on, I paused round about one month and then made that cache, which took me to "geocaching" in general.