I recommend against it.
It irks me particularly when the question is fairly new. Is there a reason (other than rep whoring) to pressure someone to accept an answer as early as they possibly can? What is wrong with giving other responders the opportunity to provide a better answer? If yours is still the only answer, you're potentially denying them the chance to learn if there are any other/better answers, since questions with accepted answers are largely ignored.
You already got an up-vote, which indicates that the OP found your answer helpful. Let them decide, unpressured, if and when they want to accept your answer as the answer. People have different reasons for not wanting to accept an answer immediately, and I don't think it's our place to try to force their hand.
If you genuinely want to help a user with a low accept rate, I'd say completely detach your guidance from your answer. Find one of their other questions in which you haven't participated, and comment there, pointing them toward the FAQ. This is a much cleaner approach, IMHO - it shows the user what the community expects, it absolves you from any rep-whoring connotations (since in that context it won't look like greedy badgering), and may (indirectly) ultimately get you the accept you were looking for anyway.