I never heard of that. I never thought that would have an effect, unless you implant late and have a short luteal phase...then it would make sense, because you'd start your period before it ever had a chance to implant...
I am an early implanter.....I know because each time I have gotten pregnant it's been on a month when we've had sex one time..so I know exactly when conception occurred, and each time...I got my BFP at 7 to 9 days later, and I feel recognizable, distinct symptoms after about 3 days after we had sex (and I only get those symptoms while prego, so I know its not all in my head). First two times resulted in live babies, the third time resulted in an early miscarriage.