With six, I don't think you have to do much. Happy fat kits though
, they look fine.,
About handling, after the initial thorough checkout I don't disturb them much as long as they are wigglers, babys need sleep and rest. After a week, when they are popplers I think it starts to pay off to handle them regularily, I take them out and pet them , hold them warm until they relax. in the long run, I would say that genetics still have 60-70% influence onn their adult behaviour.
Anyway, don't overthink it, enjoy