Bottle and pumping suggestions

I am a new mom of 3 days! Been EBF the whole time and I really enjoy it. Baby Henryk and I are not perfect but we enjoy practicing. My milk has yet to come in but the pediatrician acted worried today of his weight and lack of wet diapers. Suggested that I pump. I have the pump but have know idea how to use it. I was told by the lactation specialist the pumping before 6 weeks is no good. I'm going to reclarify that. In the meantime, when did you all start to pump and what are the best bottles for breast milk? I store milk in bags right?

I'm new and clueless!