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.
Posting announcement post to bump the thread is really a good idea to make the thread more visible to the gambling board but I doubt the tournament itself will have a better exposure here than post on the games and round section since post here can be easuly flood by discussion.
A simple 20 replies here can me the announcement post already flooded by 1 page in this thread.
With the exception of the tournament that is done like a common thing, along with other bonus update advertisements that OP want to offer, now it can be in this thread, but if the tournament is only for members of this forum, the board games and round is the solution, we see that more Many exposures on the board than in the main thread of the casino, and yes it is true that here more discussion about the casino itself, while in Papa G&R can talk more about the mechanism of how the tournament runs.
But honestly if I see the development of the tournament for the forum, people are not so enthusiastic if the possibility is small.