The lethargy should go away very quick in the beginning. If it doesn’t try to add more food. No carbs but eggs, steaks cooked with butter, fatty hamburger with cheese. Focus your fats around your activity and workout.
The only time I test is when I go off diet for special occasions and such. Then I test till I’m back on and I won’t need to test after that. I know what I eat it it has carbs are not.
Don’t fall for all the keto foods you see on Instagram or YouTube channels saying stupid shit like Keto Browniе, keto pancakes and all that crap. Trying to eat those things will keep you in constant worry and control of your diet and ketosis. They all have carbs regardless the shit those scammers pushing that crap says.
Also look into blood type diets. Cause like me I do great on steaks and red meat and feel like shit if I did the same ratios on chicken. I learnt this the hard way until another bodybuilder guessed my blood type after seeing my diet and what worked and didn’t work for me. It was spot on. He also guessed my girlfriend blood type at the time by what she ate and what worked for her and why we couldn’t eat the same type of foods whatsoever and feel good.