I find I react better to inhibitors than precursors. Huperzine inhibits the chemical that breaks down choline, so that you have more choline to use. This is similar to the way SSRIs inhibit the chemical that breaks down serotonin. DO NOT USE huperzine with a choline precursor, such as CDP-choline (citicoline), choline citrate, DMAE, etc. This will result in an overload of choline in the brain, which will have unknown effects but at the very least will give you brain fog and have many of the opposite of the intended effects. For me it takes 3 days or so for this to really kick in. For most it takes only a few hours. If you aren't getting good results from this after a week, it isn't for you. Try CDP-Choline, or perhaps a difference avenue of cognitive enhancement other than choline increase.
It works instantly for me. Probably depends if acetylcholine is the problem. Brain fog vanishes, dreams become vivid, memory improvement, motivation and mood improvement very noticeable on the same day. The down side for me is it makes me so alert I am awake longer at night and it gives me a minor headache so I cut back to every other day so I get those side effects every other day. My mother and grandfather have and had Alzheimer's and I was feeling very slow tired and foggy as I neared 70 and now I am back to 30 mentally.