Ideally according to AC21 if you case is not approved in 180 days then you can switch employment in similar job.
But there are so many loop holes, depend upon your lawyer's intrepration you need to take action.
Some lawyer interpret your case is not going to approve in 180 days so you can switch job anytime (because usually I-485 approve in year and half so we can safely assume your case won't approve in 180 days / 6 months)
some other lawyer belive, as long as you don't receive REF, which won't happen in first 180 days so you don't need to find job right way you can wait 6 months to finish and then find/ start job and when and if you get REF send current emolyment letter with some recent pay stub, and you should be fine.
So any way if you get laid off before 180 days you are not ideal situation, so take calculating risk by consulting lawyer. may be some miracal happen and you won't get REF at all. but in worst case anything could happen if you get interview in local office.
I hope this help.
JB