How long between implantation and BFP?

J

It's possible I experienced implantation on friday. I had an incident of dizziness in the morning and then severe cramping for about 30 mins in the afternoon (plus slight cramps all week before and sore nipples). I've also been super tired. Some nausea yesterday. Still getting BFNs and no AF. Now cramps are gone too.

Does this sound like implantation?

When will I build up enough Hcg to test?

Thanks!!