If you're still confusing us it just means that you haven't spent time enough on MC lately
And answering your question, I got the last achievement with 47hrs, finished the story mode 42hrs or so in, but you can finish the main story in half that. Ryza got me though, so I couldn't drop it nor bring myself to finish until I had seen most of it, which is why I took so long to complete the last main story quest. Then there's two post-game bosses which are a bit more harder than the last one and while I think I could've beat them with the equipment I had, I went to get every equipment level 999 before fighting them.