The base on mine is 400 mm wide by 590 mm deep. Unfortunately the coolant splash covers I put on don't allow me access to measure the bolt pattern. Based on my experience with other Chinese machine I would expect some variation in dimentions so it might be better to wait for the machine.
This is the dimensions of the PM932 I bought in 2012. As you can see the hole pattern is not perfectly symmetrical so I agree it would be better to wait until your machine arrives before drilling the holes.