At home Doppler

Melissa
I saw someone ask about the Doppler at the dr office but I'm wondering what's the earliest you've heard the baby's heartbeat in your at home monitor. With my last baby I couldn't hear it until 14 weeks! That may have been that I just didn't know how to look for it then. 
I'm only 8weeks now so I'm not planning on trying for awhile. Next dr appt is at 11 weeks.