The normal timeframe of a GC journey through EB3 is as follows.
1. Have LC approved. (you may skip this step if under schedule A)
2. Have 140 approved. (if under schedule A, you are able to file 485 at this step)
3. You can only file 485 after your PD is current.
After filed 485, you are considered as 485 pending.
You can change your job to a same or similar job without hurt your on-going GC processing after 180 days of 485 pending.