At what point did you know and realize that your forum was successful? When were you able to safely stop nourishing your site every little step of the way?
We generally average 1,000 posts a day. I still wouldn't consider us in the "safe zone", though. I knew my forum was successful from the community that I had. We all loved it and literally couldn't get enough of it. The goal there wasn't to bring in new members (but each new member was greatly appreciated), but to build a strong and active community with the ones we already had. And we did.
I'm afraid I disagree here. You're never safe when activity is involved. It's a great benchmark to be consistently achieving over 100 posts a day but you have to keep setting goals higher although your change in attitude will stunt your forums growth. You need to keep the enthusiasm and always aim for better. When it comes to forums, you have to move away from quantitative factors. This of course is arguable, if you set out for profit and you are consistently achieving your targets - then sure you're successful. In my eyes, profit is a by product of a community and just another incentive to keep working hard. Success in my eyes is when you have a large group of active, friendly members consistently devising new topics for discussions and welcoming others to join in the opportunity. Like it or not, forums have effects on peoples lives, many times I have had members in bad situations in which they find themselves feeling very low - be it family situations, monetary issues, whatever. A successful community has the ability to help these people with support, kindness and sympathy. The core of a community is a large group of friends so surely judging the success of a community such as a forum is judging how well those friends work well? I guess everyone has different principles though and I'd love to hear them.
This is my first goal...although I would still try and market the site long after I reached this goal.
If you started the forum with clear goals as to what you wanted to accomplish, then yes, hopefully you'll reach a point where you can say you succeeded. I think most people's ideas of a successful forum are more nebulous.
Like Savage, I disagree a bit. We get almost 1000 posts per day here, but I still think we're at risk of falling apart on any given day. We aren't anywhere near the safe zone. I define success as having a community where the members are happy, they return frequently, new members are appreciated, and the forum has general activity going on its own. We have achieved just this on the Linnie Forum; it's pretty much on its own, so I think it's safe to call it a success.
But you have plans for features to roll out over the next few months, so I would only worry about holding it together until then. Only worry when you don't have a plan!
I knew I was successful online when my contract with Protection One ended and I didn't have to look for a job. That was in 2001. My newest personal forum is new but I already consider it successful because it has information on it that isn't available anywhere else and is growing. Its growing slowly and only has 80 members but its growing. I can use it as a platform to share information on using vBulletin that I can't share if someone asks for official support because of company policies on supporting customizations.
Any forum is at risk of falling apart on any given day. I was motivated to register here and post reasonably regularly, that's pretty rare for me so there must be something working here. I like the non-stuffy yet still serious style of conversation.