As BiggJuicy said. It is based on the ester attached, which determines the life of the drug. Enanthate, cypionate, hex, ---- long esters, propionate, acetate ----- short esters.
I would wait 72 hours from last pin of the prop and as stated run it longer than the tren. Keep eating as if on cycle.
However, depending on what you are taking for PCT (HCG, Clomid, Nolva....)- opinions may change.
post up what you plan to take and I am sure many will critique