Well, I am a working freelance mom & my 13m/o bb's dad is full time at home with her.
Right from birth, I reminded papa to keep talking to bb all the time, no matter what he was
doing; to say he is making milk, we are going to bath, play or sleep.
I do think it helps as bb started to babble mama/papa at 7 months & at 8/9 months
she can say bag, bus, pants etc.
Keep on talking to bb even now, but as of few months back, I notice she has her own thoughts,
so I give him time to express herself, give feedback. But honestly, I never keep track on how much
we talked, just keep going