Finally did this before going away to World Pride a few weeks ago. It took seven hours and four people at the hairdresser's - involved bleach, treatment, toner, blue dye, haircut, more blue dye, fixing the cut again, and a blow dry. Such a long process but I only plan on doing once. I found I've spent longer with gradually lightening shades of green hair (over three weeks so far) than I did with blue (about a week and a half).
If No Doubt come to Melbourne during my 101 days (and I like their new album) this would be a perfect time for the goal. Annoyingly this is more associated with Katy Perry now, but Gwen Stefani was very much my inspiration!