You need to draw your spline so that what will be the center axis of the bottle aligns with the scene’s Y axis (green arrow). Then when you add a lathe object, and drop the spline into it as a child, the center axes of both will be aligned and the lathe will sweep the spline around that center giving you the bottle shape. You can then move the lathe object wherever you want.

(Edit: I didn’t see Adam’s response until I finished mine.)