I think it’s a nice courtesy, you’re going to need time off in a few months. It likely won’t be covered for actual maternity leave either so you won’t be guaranteed your position when you return. I personally think it would make your boss and coworkers untrusting if you took the position, knowing you can’t fulfill that position in a few months. I’m seriously all about being up front. There was another post here recently where they didn’t even want to tell the hiring person they had children. You’re going to end up in a very stressful position.

I wouldn't say anything until it interferes with the job directly.

You don’t need to disclose pregnancy during the interview process

I wouldn’t say anything until I got the job.