In a persuasive essay, normally in middle/high school, you have a topic and three main reasons to support it. And those three main reasons are in their own paragraphs. So If you want to put "My thesis" it would work like this... My thesis is true because of (reason 1), (reason 2), and (reason 3).
Though wouldn't use My thesis because it doesn't have the "topic/prompt" of the essay/assignment. Like if the prompt was Should we do more to save trees? Yes or No? Why? You could write We should save more trees because (reason 1), (reason 2), and (reason 3). Or We shouldn't save more trees because (reason 1), (reason 2), and (reason 3).
Does this answer your question? Or no? Because your question was unclear.
Due to the nature of an essay the thesis statement is generally always in the first paragraph, in this case the very first line is the thesis statement.
