If you only have Poetics (120) you will replace them by Lv 52 with quested 125 HQ gear. Since the main story quests now award 110 gear, there's no need to farm Poetics unless you don't have access to those main story quests. Then the quests in the first leveling zones in Ishgard will start awarding 115 HQ gear (req. Lv 50), so there's a smooth progression already.

Poetics is better used to buy accessories for your second and third jobs, since they may not have access to a full set of quest gear, depending on what jobs you play.