Results may vary. Your hair may easily adjust or it may undergo a transition period. During transition, your hair can be greasy at first. This is just your hair overcompensating the oils because it is already used to producing more oil to replace what commercial shampoos strip away.
This may last for 2-3 weeks, depending on your hair. Best to use consistently and observe. While you're at it, just be patient, let your hair adjust and get used to this goodness.
Nevertheless, the aim of reducing plastic, may it be a shampoo sachet or a shampoo bottle is a great motivation for us to use Shampoo and Conditioner bars as it lessen the waste footprint after using it. #guiltfree