Cramping: Implant or AF

Hi Ladies,

Curious how soon you cramp before AF. Been TTC for 2.5 years. I had Endometriosis and learned it had returned. Had surgery in Oct. to remove. They also found fibroids and removed. Was cleared last month to try and just finished our second round trying since surgery. ovulation test was weird so I believe I am 6-8 days post ovulation but period should be about 8 days out. Having cramping today. Low abdomen and lower back. I am obviously doing lots of research online and driving myself crazy. I guess I just want to know how many of you experience cramping that soon before your period.