It can take upto 90 days from the day they receive ur application. That's why we all apply in 1st week of March to start our OPT by 1st week of June, even though we graduated on 2nd week of May.
You can always check your OPT card status, and you can also do case number if you need quick response from USCIS.
When I renewed my EAD (STEM OPT), It took me more than 60 days to receive the actual EAD card (hard cover).