If you're using Ttokkyo, 600 mgs is easier to draw. I like 400mg-600mg as a dosage, so either way is fine IMO. Maybe 400mg if you're new to it, 600mg with subsequent cycles.
Im on 400mg a week for 8 weeks, just starting week 5 and im very pleased with the results thus far. This is intended to be a light cycle, and im starting to notice some size increase already...
I'm taking mine all the way to 800mg,will be at 600mg this week haven't seen any problems ,strength is up and appetite is great, will let you Know how 600/800 feel.