Derrick, many people seem to find ketoadapting, especially to a zero-carb woe, difficult. Stephen Phinney, in Ketogenic Diets and Physical Perfomance, says "There are to date no studies that carefully examine the optimum length of this keto-adapataion period, but it is clearly longer than one week and likely well advanced within 3–4 weeks. The process does not appear to happen any faster in highly trained athletes than in overweight or untrained individuals. This adaptation process also appears to require consistent adherence to carbohydrate restriction, as people who intermittently consume carbohydrates while attempting a ketogenic diet report subjectively reduced exercise tolerance." (My emphasis)
And in his newest blog post, Dr. Mike Eades talks about keto-adaption.
I didn't have much trouble, but that's possibly because I'd been VLC for the previous two years. Other folks will probably tell you to ease into it, but I'm an all-or-nothing gal myself, so I'm going to advise that you rip the Band-Aid off all at once -- just get it over with. Your choice, of course. ;D