Weekend-- Primo is super slow grow.... quality gains, just slow. I wouldn't use it for anything less than 16 weeks. Just my .02. And when it takes 800 mg/ wk to do what 100 mg/ week of tren will do... the cost:benefit ratio needs to be considered.
GrapeApe-- On the matter of being concerned with shutdown.. use hcg on cycle regardless of cycle length for extra insurance in your post cycle recovery.