Let me know how it goes, I have taken it 3 times, and prepared several months, about 1 to 2 hours per weekday, before each exam. I used the CalGeo videos (it will take you hours just to organize the pdf handout from CalGeo, and for me was not helpful), and many of the references the Board. The Board material is very vague and also was not helpful. The passing rate is at about 20 percent, a couple years ago it went up in the 30's. The exam content varies, but some of the questions are very good, while many others are terrible.
I have been in the geotech field since 2002, geotechnical design and consulting, and have a master's in geotech. In my opinion the exam, besides some good questions, is generally poorly written (and I don't think they take the time to throw out 'bad' questions), and with only 100 exam takers per year, may not get the attention it needs like the civil, and structural licensing exams. Good luck, and let me know what you think.