So, someone has answered your question, and you haven't even waited a full hour yet. That's great! As you might already know, the Stack Exchange model encourages you to accept an answer from those given. As one meta post says:
Accepting an answer is important as it both rewards posters for solving your problem and informs others that your issue is resolved.
However, that post also says:
You might wait 24 to 48 hours to give other people a chance to give you a better answer. A question with an accepted answer isn't as likely to receive further attention as one without an accepted answer.
I wholeheartedly endorse that recommendation (I've often said 12-to-24 hours, instead of 24-to-48, but the sentiment is the same: give others time to look at your question before accepting an answer).
I think waiting is especially appropriate for a learner's or a language forum, for a few reasons:
Your first answer may not be a good one. Few things on SE are more frustrating than to see someone post a really good question, then see someone else dish out erroneous guidance, and then see the O.P. accept that answer just a few minutes later! That first answer might sound good to you, but how do you know that the matter is truly settled, or that the answer you've been given is even a good one?
Your answer may not have been given by a native speaker. This forum has learners helping other learners. I have no problem with that, but, every once in a while, someone will provide an answer that's off the mark. Don't assume every answer you get here is infallible (even native speakers are wrong sometimes).
There is often more than one way to look at a language question. Getting a one-and-done answer might work on a Programmer's exchange, where a snippet of code might help you solve your immediate problem and get back to work. But English questions can't be tested with a compiler and a few test cases in the same way a C++ question can.
Accepting an answer early makes people less likely to look at your question. This makes it less likely that you'll get another answer, but, equally important, it makes it less likely that people will take a good hard look at the answers you've been given, so a truly bad answer might be less likely to get the comments or downvotes that it deserves.
We have users from all over the world. You may ask a question in India, or Iran, or Italy, and accept it an hour or two later. Depending on what time it is, there's a good chance that no one in the United States or Canada has even looked at your question yet – they're all asleep in bed! There are enough differences in AmEng and BrEng that you owe it to yourself to let the whole world look at a question before considering a matter settled; we all might learn something new.
Accepting answers quickly may encourage quick answers. Some people might race to answer a question fearing that they'll lose a chance to earn rep if they take their time. However, some questions are tougher than they might first appear; perhaps these should take some more time to answer, or be improved with additional research. Let your question percolate in the minds of the community for awhile.
As much as the person answering your question might appreciate a quick 15 points, please, give it some time. Allow ample time for others to evaluate that initial answer: to offer corrections if they think it's not accurate, amendments if they think there's more to the story, or alternatives if they think there might be more than one good answer to the question.
Your question might end up better as a result, and ELL as a whole might be better off, too. Accepted answers that seem hastily written or downright unreliable will neither bolster our reputation nor encourage newcomers to return.