This is a tough one, because flavor intensities vary widely. A few drops of Lorraine's lemonaide in a 10ml bottle can overwhelm some flavors. Cherry and coffee too. Vanilla and coconut could take many more to affect. You might taste just one drop of the bubble gum and see how strong it seems.
A good way would be to have a drip set up - some VV batt with a 510 2.2Ω atty with a drip tip. Then have a 3ml bottle of the premix and add a drop at a time, shake and test. If one drop is undetectable, add two drops at a time. If two doesn't do it, add
three, testing each along the way.