Xiaobaitu and other experts, Please help!

My NIW I-140 has been approved. I filed I-140 3 months ago. So there is long way to go to file I-485.
I would like to get your suggestion whether I change my job or not.

When can I change job? Now or wait unitl I file I-485?

Should I wait for 180 days after I file I-485?

How risky it is that the I-485 will be denied because of changing job? (do you have any statistic information?)

What is the chance to get an interview for I-485?

Thanks!