I don't know if anyone cares but here is what I found after calling my international student services. They didn't have an answer right away so they told they will inform me after they find the right process. After couple of hours they emailed me. 

“A student may change employers during the 17-month period, but all employers that a student will work for during the STEM extension period must be registered in the DHS E-Verify program, and the student must report the change in employment to his or her DSO.”

I replied back "What about changing the employer before the 17-month period has started and application for 17 month extension is pending?"
You just need to report when you terminated your employment with the previous employer and report the name, address, contact information and start date with the new employer.

Thank you  everyone who took time to reply to my post!