Apparently the kyuubi's demonic chakra or his overwhelming pressure was enough to give my body a shock that my chakra got unlocked. Unlocking chakra naturally is very rare. For clan kids, the clan elders in the family would unlock their chakra at the appropriate age. And as for the civilian kids with no ninja in their family, would unlock their chakra in the with the help of academy teachers. Unlocking chakra at a young age is frowned upon because even though it may give a slight head start, it usually has a detrimental effect on the body. Young children are more prone to outbursts and therefore have abysmal control and may subconsciously overexert their chakra beyond their capacity, which may damage or impair their chakra pathways and that could lead to adverse problems ranging from temporary disability to crippled chakra network or even death. But these things have nothing to do with me as with my cheat.. I mean perk of Jagan eye, the chances of my chakra getting out of control is nil. Hence I happily continued to exploit my cheat to train my chakra. It was really hard as first I had spent almost thirty years without having any such magical energy and hence I was unused to it, And boy am I a genius! Who am I kidding, the fucking jagan is a fucking cheat. All I have to do is to let the chakra continuously flow through my body along the chakra pathways, try to release it a bit outside the body from time to time, and lo and behold! The control over my chakra increases. Such bliss!