breastfeeding and plan b

i called the y lactation nurse and asked about taking plan b while breast feeding, she said its safe but better to wait to feed him directly from my breast for 4 hours, in those 4 hours i wasnt able to "pump and dump" but im able to pump now, should i pump out a couple oz and then feed my son or does the pump and dump method not matter since its been 5 hours since feeding directly off breast