Hello Telly.Rollinger,
Method doesn't have an automated clock that can perform actions. You will have to have a user click a button (or some other physical action) to activate a send email action. You can have a button that finds all the customers who joined 30 days ago and send them an email with the click of a button. This would be a customization in Method.
I'm not sure off the top of my head if MailChimp is capable of automated emails. You would have to check with MailChimp. There is an article on MailChimp automation that you can take a look at. With a very quick check, it looks like you could load contacts in Method to a MailChimp list and have its automation system send out emails. The issue is that you need to manually upload the list/contacts from Method to MailChimp.
Greg