I got an extremeley, EXTREMELY, very light barely there, only showed up after about 15 mins, was SURE it was an evap line on two internet cheapies from ebay at 12DPO and 13DPO. I had taken a FRER at 9DP0 and a few more cheapies before that that were all BFN's.
I didn't get my BFP until 15DPO on a Clear Blue digital test. Took more cheapies since and the line is there but still light!