Huge job opportunity at 29 weeks

Hi ladies! I just graduated with my degree in social work last month, and I was called for an interview in my top choice agency today! Here's my question though - I'll be 29 weeks when I interview, and I'm not sure if I should wait and see if I get hired and then tell them I'm pregnant (I can still conceal it a little) or if I should be open in the interview and tell them off the bat. I'd have to take leave about 2 months after I start, if hired. I'd wait too he's born, but I was on a stipend with my university and part of the terms is that I secure a job within two months. I can ask for an extension I suppose, but I really wanted to see what would happen before I did that. This is my dream job and such a good opportunity! Please give me some advice.