implantation

update**** [i tested today (prematurely). i took a dollar tree test instead of wasting my 13 dollar FR due to my own impatience. i got a BFN, of course. today makes only 2 days after what i believe was implantation and i also didnt use first morning urine. it was like 6 p.m. when i took it. I am going to test again on Friday, March 16 the day my period is due.]*** i experienced what i believe is implantation bleeding and cramps on yesterday, March 11. when should my hcg level be high enough to test and receive a clear result? i bought first response brand.