You might want to think about your setting and how your data setting represents your business question, especially what information would be available at the time of the prediction, and how long you would want your model to work.
You might benefit from this debate and the accompanying example workflow.
BTW: If you use a target (your coefficient) it would be called a supervised learning. And to predict a new month you would use a predictor not a learner.
A very basic example could be seen here: