My systems usually come in a bit dense and have to be thinned out (very cautiously so the longevity of the system is considered). Poofiness does go down but some will remain if the density is too heavy.
When I get a new system cut in I usually book a 5-10 min follow up cut about a week later. That way I can live with it and get a feel for what will work long term and what needs to change. I almost always end up having a bit of length and density taken off when I go for the follow up.
Better to be overly cautious for the first cut - once it's cut or thinned it's gone forever. On the follow up you'll be certain about what needs done.