At what week do doc start using Dopplers?

Mexiflower • Hi im Christine. and we are trying for our last baby:) i have a girl12 boy10 girl5 boy4 girl1

I'm 7w5d next appt at 8w5d. Do you think they will try the Doppler? I've had to appt at 5 and 6 wk. But this is all that was seen. First pic is 5wk.

Second pic is 6wk.

So I'm still confused if there's a baby in there.