Yes, I ovulated on day 27 which was 3 days before my period was due. I know because I had the CBFM and a CB opk and I always get ovulation pains.
If you ovulate late, you can ovulate four days before your expected period (and then your period would be later, your cycle longer that time). Does that make sense? but you don't ovulate 4 days before a period--- the pattern of our cycle doesn't work that way. good luck