That makes sense. I'm going to get the test strips and find out when it is, but it is not instant. I believe it takes at least an hour or longer, but I'm only measuring that on how I feel. What I've found interesting, however, is that the effect does last a long time once it kicks in, similar to beets which max out for 12 hours (according to the Nitric Oxide Solution).
Dosage with this stuff, I've found is almost unbearable for me at 3g. I'm now just going a little below the spoon to avoid any heaping dose, and I can now handle close to 3g per day, but it took me several days to get there. Also, do not take this stuff after 6pm or so, or you won't sleep well. At least that is how it affected me.
Side note - The Chinese say never eat watermelon at night, it will keep you up. Watermelon seeds are highly diuretic, I learned that the hard way