How to have my units be drip content

Hello, first of I want to say thank you for all the support you have given me up to this point. You guys are great and have helped me tremendously! Now my last delima... I want to know how I can change my units into drip content. in other words, I have a course that has open enrollment at anytime and I want to know how I can take my units and make them come out every 7 days. So if someone was to join the course today and another person come in a month later, I want them to be able to have the units drip out every 7 days. Is that something I can do? If not, do you have any other ideas for me to make this happen? Thank you so much for your help!!!