Keep practicing, and pay special attention to your base whenevr you are in the sort of positions where kimura setups are likely
I learned the kimura in my first month of grappling, but it wasnt until my base improved and I stopped giving them the guard back cheaply that I started to go for them on top. Once they were all about defending the neck from guillotines, darces etc the kimura just pops right up.
My tip besides keep going for it, is not to solely focus on going for it either. I feel its something that pops up quite often when they are aware of chokes and armlocks and are more likely to give up the kimura grip when their escapes become mosre hasty