Honestly, who you give the check mark to, if anyone, and why is mostly up to you, barring fraud/socks. It doesn't really matter if you accept an answer or when, it doesn't prevent anyone else from answering. While users might be less likely to answer if there's an accepted answer, that's up to the individual user to decide.
Really, the accepted answer is more supposed to signal "This answer worked for the OP." If you have an answer that works really well for you and you think it the best, go ahead and accept it if you want. Or, go ahead and wait to see if a better answer shows up. That's entirely up to you, and no one will (or should) tell you otherwise. If you pick an answer that the community doesn't agree is best, our model is supposed to allow for the "community chosen" answer to rise up via votes. While it won't surpass your accepted answer, which is pinned to the top if the asker and answerer aren't the same, it will take second place and the score differences can tell future users what the community thinks.
As the OP, you're not always the best equipped to choose the "best answer," which is why we allow community voting. If a later answer comes in that's better, in your mind, than the accepted answer, you can always accept the new answer instead.
It should also be noted that the post you quote says "you might wait" and doesn't say you have to or it's expected. The only "have to" is you have to wait at least 15 minutes* to accept an answer to your question.
It's your accept vote, select the answer you feel best answers your question or helps you the most. Don't worry about when you accept it, you can always change your mind later. Likewise, you don't have to accept an answer if you don't want to, for any reason.
* 48 hours, if it's a self-answer.