I read here that 日本語の勉強は常用漢字を全部覚えてからが本番だ。is a valid sentence but 日本語の勉強は常用漢字を全部覚えてからのが本番だ。is not. This reminded me of a question I once had. I do understand that particles are classified into different types
(but a person with no linguistic background like me most probably doesn't understand how they are classified) and are better explained in the Japanese Wikipedia article. Can particles of the same type be joined together?
There was already a question concerning this before; I was wondering if there's a general rule concerning compounding them and how this relates to the particle classification.