I think this is right in broad strokes, but what you call "a few years" is '73 to '81, kind of a long time to "kick it" because your plan went astray.

Furthermore, Quiddle also often talks about his motives in terms of what he found "amusing," "felt like," or "pleasant" (in conversation with Hermione). Then there's this:

"You know, Mr. Potter, if He-Who-Must-Not-Be-Named had come to rule over magical Britain, and built such a place as Azkaban, he would have built it because he enjoyed seeing his enemies suffer. And if instead he began to find their suffering distasteful, why, he would order Azkaban torn down the next day. As for those who did make Azkaban, and those who do not tear it down, while preaching lofty sermons and imagining themselves not to be villains... well, Mr. Potter, I think if I had my choice of taking tea with them, or taking tea with You-Know-Who, I should find my sensibilities less offended by the Dark Lord."

I think he's not quite so given to long-term planning as you imagine.