Ideally, it would be placed in Burma, but I usually land it in Kwangtung. Each area has it’s pros and cons.
Burma - highest mobility and range, but more susceptible to attack.
Manchuria - low mobility, relatively safe from attack, but direct shot to Russia
Kwangtung - best defense, average mobility on land, high mobility in the sea, susceptible to the Kwangbang attack
In my experience, I took China J1 and placed an IC on Kwang on J2 (I think). This was after whittling India. It’s a nice pocket to be in, but if things went better on J1, I’d go for Burma. In the last game I played, this IC was VERY important because the Allies placed ICs in Sinkiang, India, and Australia (US1, UK 2 or 3, and UK 5, I think). Nevertheless, I went on to own 6 ICs that game….
I try to place an IC on J2, J1 might be a bit risky and costly. It could be a trade off, though. Place on J1 to defer transport costs to tank and inf, or Place on J2 and have a sound fleet. Not sure which way to go, but the earlier placed, the better.