You're simply not priming it enough. Kendo cotton requires WAYYY more priming than what's written on the package.
A good practice would be:
After fluffing the ends up, using ur ejuice dripper to dab e juice all over your fluffed up cottons. Make sure that the sides, top, botttom and even the centre (the ends basically...) are slathered with e juice.
Make sure the cotton that runs into the coil are completely saturated eith e juice. This can be done by dabbing the dripper tip directly onto the cotton. Drip some on the coil.
If the whole process is done correctly, u can actually get about one and a half dropper worth of e juice onto the cotton.
Next step would be to fire up your mod and blow at the cotton/coil assembly. Fire for a good 5 seconds straight at 60% of the wattage you'll be vaping at.
After this is done, you'll notice that the cotton that's sticking out from your coils start to turn translucent. This means that the cotton inside the coil and nearest to the coil has been primed.
Drip more juice over the cotton and fire your mod for another 5 seconds while blowing at it.
Repeat this step 10 times.
Also, try to bend the fluffed up ends of the cotton so that they're above the coil as heat is what helps in priming it and in no time, the entire cotton and fluffed up ends will turn translucent.
Once this is done, set the cotton back in to cover the juice holes and spread them out nicely.
I've been using Kendo cotton for nearly half a year already and I find that it requires a bit of tlc and patience to set up in order for it to wick properly.
Hope that helps.
And no, a little too much cotton wouldn't hurt as this cotton is absorbent AF.