I had a post moved recently because the page had gotten too long, how can I tell when to start the 2nd page. The last thing I want to do is annoy the mods by making them have to correct me.

I'm not sure what you mean. Posts automatically go to the second page after so many replies (usually 15 or 20, not sure what it is here, never bothered to notice), and posts so old usually get pushed into another page of the forum due to age.

I assumed it was moved, I posted at the bottom of the first page("Quick Reply") and when I got a reply it(my post) was on the second. Anyway, I guess I just assumed wrong.

That means the first page was full of posts, so yours went to the second page.