Most guys won't notice a plane being a little out of balance.

However, everything the other guys said is right on. The more acrobatics you do, the more you'll notice it, and the more low speed flight you try, the more you notice it. For joe sport flyer, the most important part is dropping a wing on final approach. A balanced wing will stall off later at a lower speed, even though it's heavier.

My "no measurement" way of balancing a wing is to not worry about it, and go fly. Then, take the plane up high, and do a series of low speed straight ahead stalls. Or, pull full-deflection loops until the plane snaps out. Look to see which way the plane rolls, which wing drops. If it always goes the same way, add weight to the "high wing" until it goes both ways equally, or better yet, stalls straight ahead.

Doing the flight testing will also help you get more familiar with your plane's stall handling, which is a good thing.

It's worth doing.