@klardotsh I'm not sure how to explain it. I think it's a bit like asking a smoker when the feeling of having a cigarette comes back. Caffiene is a quick fix or a workaround, and you'll probably have been using it to mask something else that's the problem. For me I get lots more done consistently but look more sluggish?
Do you have any neurology conditions? If you have something like ME, narcolepsy, or ADHD, you'll want to be careful about dropping a stimulant out of your diet.