Great that you've started taking action! Loving the all nighter
You're going to have to find out what works best for you, to be honest.
The general consensus amongst those of us who do this is to "warm up" your forum account a bit by posting a few genuine posts, then posting a link from within a relevant post in the thread you suggested.
But to be honest... I barely do this. I'm more of a necro-old-threads-type-of-guy. I do not wait. I spam
It's simply too time consuming to register on forums and participating in discussions before throwing a link into the mix.
If you decide to necro old threads, make sure you bookmark 10 for example and see how many of those are still live after a week or two. Sometimes it's 5, sometimes it's 3, depending on how well you do it.
I usually include a paragraph in the beginning of the post saying something along the lines of "hey, I'm sorry for bumping this old thread you guys but I saw nobody even bothered to mention this..." as an excuse for necroing an old thread.
Some old forum posts get a bunch of traffic every month.
The best forum posts, of course, are the ones that are still relatively new.
But those are not many in the niches I've chosen. Hope this helped shed some light on this method.