It's best to take at least ~400mg of EGCG at one time. The NP is 50% EGCG, so this would be ~800mg of extract at one time.
To quote an article by David Tolson:
"...The most important thing to note is that green tea polyphenols undergo saturable presystemic elimination. This means that low doses only increase plasma EGCG levels marginally, but once the point of saturation is reached, the same amount of tea will have much greater effects.
"The amount required to achieve saturation in humans varies from study to study. Using tea leaves, one study found 3.0 grams to increase plasma EGCG levels by 2.7-3.4 times as much as 1.5 grams, while the difference between 3.0 grams and 4.5 grams was not statistically significant [90]. However, a study measuring antioxidant potential of green tea leaves found that 2.5, 5.0, and 7.5 increased plasma antioxidant potential by 2.1%, 6.2%, and 12.7% respectively at the 120 minute mark, indicating that 7.5 grams was over twice as effective as 5.0 grams [61]. 7.5 grams equates to about 375 mg of EGCG (note that this is only an approximation), and a pharmacokinetic study with green tea extract yielded a similar result. Amounts containing 225, 375, and 525 mg EGCG raised plamsa concentrations by 657, 4300, 4410 pmol/mL, respectively [91]. However, in a last study, despite the fact that 400 mg EGCG (from an extract) overcame saturation as opposed to 200 mg (the AUC, in this case a measure of total bioavailability, was 23.0 and 64.9 respectively), 600 mg and 800 mg amounts kept getting significantly more effective, with AUCs of 111.1 and 258.2 respectively [92]. The maximum plasma concentrations similarly increased. It is also noteworthy that this study found that it took 600, not 400 mg of pure EGCG (without other catechins) to overcome saturation, once again emphasizing that the other catechins operate synergistically with EGCG.
"With this data in mind, we could safetly say, for example, that taking an extract containing 400 mg EGCG once daily would be considerably more effective than 200 mg twice daily. Increasing this amount to 600 mg may or may not have a significant effect, depending on the study we look at. Either way, a minumum of 400 mg EGCG should be taken at a time to overcome saturation. An ideal dosing schedule would be 400 mg 2-3 times daily, while a more economical (but still very effective) one would be 400 mg once daily (preferably in the pre-workout period)."
I personally take 800-1000mg extract (400-500mg EGCG) 2x daily.