Usually, when you leave your baby, you probably feed right before you leave and right when you get home. I m not sure how efficient it is. If it is not a double pump, you may need to take another dose of oxytocin for the other side. If this pump is not electric, you need to get a good electric pump. The brands I recommend are White River, Medela and Egnell.
Most mothers do best if they pump both breasts simultaneously.
The usually time is two weeks. Sometimes we give a second course of therapy. In this case, where you have a healthy baby, it would be better to try other measures and avoid a potent drug like Reglan. If the oxytocin helps and you find that it is a letdown problem, this is probably related to pumping. Mother Nature gets the idea.