So you wanna make your new forum successful, right? What you gotta do is offer something people can't get elsewhere, so people have no choice but to visit your forums. If people can get the same things here as they could at your forum, they won't bother going because there's no point.
So what do you have to offer your forums? Your games and your posts. You have to make a commitment to make your games and posts exclusive to your new board. If you make even a couple posts here after your new boards open, people won't bother visiting your forum because you're still posting here.
You should start this as soon as possible, and don't look back. If you make ANY "why aren't you joining my forum" posts here or there, you'll just look desperate and less people will join. Just make your normal posts there like you would here. Things will start slow, but you have to be consistent or else it will never grow. One link from here is all you need, anything else just seems needy.
Hope this helps.