As some of you have written out here, there might be some confusion over 2 months or 60 days. Remember that it is 60 days and not two months after graduation that you can start your OPT. Same is true about grace period. While it is almost 2 months, you need to literally count the days as some months have more than 30 days. So, make sure you don't fall out of status just because of 2/3 days.