For a 1/4" cut, or pea size:
I do the 1/2" cut carefully with the harp in a grid pattern. That way I know each cube is 1/2" in size. Then I just stir with the 1/2 harp until most cubes are reduced to pea size. This is usually about the first 5 minutes of stirring. Then I switch to the perforated spoon for stirring once I'm satisfied with the curd size. I do get some grain sized curds though, it's not perfect. That's why I created the 1/4 harp, I wanted to achieve the pea sized cuts more efficiently.
I'll try your strategy. So you do 2 "X" cuts, then 2 "Y" cuts then horizontally?