At home fetal doppler: safe?

How often did you use/are you using your at-home doppler? I have read some sites say 5 minutes every other day, some every day. I just got mine and am almost 10 weeks. I have found and heard baby’s heartbeat easily every time I’ve used it so far so I am really happy with it. I know it’s her because it’s over 150bpm and I can definitely tell the difference in it and my own heartbeat. We know the baby is a girl because we had the embryo tested before IVF transfer so I love to make sure she is okay. It’s just so nice to hear after years of failures.