I'll advice you take this post and modify your OP to accomodate this tournament as it will be missing in between threads and the participation will be very poor and not encouraging.
Not everyone has to scroll to this particular page to find out the advert but it can be seen visibly in the OP once one opens the thread.
Part of this kind of update is why people often reserve their second post after the OP
I think the post on the thread is a good Idea as it did help the thread to come on the first page. That is the reason you were able to see the new offer and I was too. That means more members would be able to see the new update. I think adding it on the first page would make the ANN page clutter, which is never advisable. OP did what was right for vbetFTN as the intention was to get more views.