For me it took 2 days to have my verry first. But then it took like 2 weeks to have another one and now after abaout 2 months im having abaout one a weeek
Like Zizou said, it depends on your motivation. A week or two for some people, others longer. You can read up some info here about the techs, I myself like WILD.
Next chance you get, go introduce yourself in ‘The BIG “Hi, I’m new here!”’ topic in the Gathering. =]
It took me something like two months to have my first proper lucid dream. But I had some periods of time when I didn’t do RC’s at all and didn’t think about LD’s so much.