Okay, I have used VZ cherry super concentrate along with a hoard of countless other cherry flavorings I have given away or been so disgusted with Ive thrown em straight in the trash. VZ cherry is salvageable at best as far as cherry goes. 5% is the max you can as a standalone flavor. Dont bother going higher, it will sadly get even weaker in flavor.
For your first time out Id have urged you to mix anything BUT cherry. Ive been at this over two years and have yet to find ANY good or.worthy cherry flavoring by any known, or even unknown manufacturer. My grail for cherry is a jolly rancher type cherry flavoring. Even a ludens type cherry would suffice. Sadly, there are none, zip, zero, zilch, nada. You might find one that doesnt taste like cough medicine but then it is weaksauce flavor wise at any concentration. Cherry is the one flavoring that is my nemesis. Dont suggest any, Ive tried all you can think of and ones you cant, mixing ideas galore, they all just plain fail and fail badly.
In short, its not you. Its the product.
Now if you want vz cherry to work at all, lose the sweetener, it always makes flavors go flat and weak within 3 days. If you absolutely have to use sweetener only mix enough to last a couple days. I suggest 5%-6% max flavoring. Any more will not improve it or make it stronger.
Another note: 10% ethyl maltol is a ton of sweetener. There is cotton candy flavoring and cotton candy that is ethyl maltol. EM is the one commonly used to sweeten a little bit. Going full out 10% will kill flavor in any juice. EM is used more to round out sharp or harsh flavor notes in juices, and in minute amounts. It really doesnt make for a good sweetener, but that result is best between 1%-2% tops in my opinion. But remember it will dull flavoring within days in any amount.
And do not leave the cap off with fruits unless they smell of chemical overtones. If so, 12 hours max. It will not improve beyond that. Vz cherry does not have that chemical overtone so leave the caps on or it will just get weaker.