need input or advice ..

Autumn
I'm 24 weeks and have been applying for jobs even though I personally it's pointless by this time but it's a requirement I have to do for my assistance. I got a call for an interview for tomorrow at around noon , I forgot to disclose over the phone that I'm expecting or would you ladies wait to disclose that at the interview ? It's a at the golf club outside of where I live and I just don't know how to disclose something like this. 
Thanks in advance