Using TI to create automatized reports

I am currently working on a project which involves multiple monthly reports. The company's idea is to try to rely as less as possible in manual work. They need comparisons between months (i.e: last three months: dec, nov and oct), last year,etc. . In most cases, it involves conditional functions, like "all values from december which were made manually".

I am new to Power BI and even more to DAX, so as you can see I´m struggling to find a solution. As I see it, one way is to make reports with charts fed with values based sorely on DAX functions, more specifically TI functiones.  That way, every month the only thing we need to do is refresh the .pbix doc with the new data input.

I am not sure this is the right way, or if there is a better, more efficient one. 

Any advice regarding this issue, or wiki, video, article, would help.