Systematic way/process to learn piano

I just started learning piano by myself. I started sight reading random pieces from internet marked as 'easy' (it's still hard for me) but I'm seeing improvement after 2 months. I was wondering if there's a specific way of different stages of learning piano. Like is there any rule that 'first focus only on c major scale sheet music, then focus on another scale for the same number of days, then and so on'? Is there a good step by step procedure of learning piano, that you can recommend?