The best answer I've found for this (from here
There are two reuptake mechanisms for the acetlycholine system to re-use choline, or bring it back into the presynaptic cleft. Generally speaking, if acetylcholine is used up quickly the high affinity transpoter (which is Na+ dependant) will reuptake it very quickly which results in a quick rise of levels in the brain. For the daily intake of choline though the low affinity transporter regulates the levels.
Free choline will be floating around in the blood if there is too much, but available if the need arises. So it's not necessary to take right before or during the intake of racetams, so long as there is enough available.
In my own tinkering with Alpha GPC, I found that taking 300mg a few hours after my first 800mg dose, and another 300mg after the second, seemed to ward off the brain fog. But I think taking it together worked out ok too.
If you're dosing only once with choline, I would take it between the piracetam doses, and see if you get any side effects before, or later in the day.
Edited by chrono, 14 April 2010 - 07:11 AM.