Ovulation Within 10 hrs of positive OPK ?

Kelly • Mother of two beautiful children!
Is it possible to release my egg within 10hrs of my positive OPK? My OPK was super dark positive at about noon yesterday, intercourse at 2pm and then had awful cramping for about half hour around 10-10:30 that night. I had to get the heating pad out, I couldn't fall asleep the cramping was so bad. 
Was that ovulation?