If you're 8.7% then don't worry about cutting at this time.
Some reasons: First, clearly at least in this point in your life your body is able to be fairly lean pretty easily. You will find cutting back to the same bodyfat that you are right now to be pretty easy.
Second, on having a particular, timely reason to be more cut up than you are right now, if that becomes important at some later time, after easily getting back to the same as now, which I'm confident you can if you don't fatten up unreasonably, you'll be in such close striking range to being genuinely lean that it will be a fast process.
You're at an ideal time for some great growth. Why stint it by cutting, when you truly have no need at this point.
That said, don't fatten up ridiculously either. For example, try keeping waist size gain to no more than half an inch a month. Even 1/4 inch shows you're eating enough to grow well at this time. If you increase by say 2 inches over time, then consider a quick cut and restart the gaining on that being quickly accomplished, as I'm sure you'll be able to do.
The waist figures are assuming that that is fat increase causing the size increase. It may be the case that you'll have a muscular thickening of the waist, which often is a good thing. It usually is not rapid though. The above is just for illustration.