Interview Advice

I have seen several posts about this, but my situation is a little different.

I have been with my company almost three years. Back in April, I started working from home which I love, All of my meetings are virtual. However, I recently applied for another position within my company that would let me continue to work from home and I wouldn't be on the phone all day, so I could keep LO with me a few days a week. I was notified today I'll have an interview in the next few days (they're only interviewing three people for it) and it will be virtual, like my meetings have been. This is a one-person position; I would have an assistant, but they would do minimal assisting, as she is more of an assistant to the whole department.

So being almost 24 wks, how do I bring up "I'll be taking my maternity leave starting mid-September" into the conversation? They won't be able to tell I'm pregnant, so I have to bring everything up myself. It's only through the computer, so there is no video conferencing.