Processing time for status adjustment varies case by case and your geographic location.
The USCIS has a website that informs applicants of the current processing time for applications. Currently, adjustment status based on the service center ranges from 15 to 18 and a half months, but this changes frequently. The website is updated roughly every month.
To do this, go to USCIS.gov and look for processing times, then select the specific form number and service center where your petition is being filed to see the current processing time.