To tell or not to tell. ..

Ok so here's the deal. We have been trying for number two for about 2 months. In that two months I have been going on interviews for a new job. I landed an outstanding offer that is going to start out paying 25% more than my current salary! I'm in heaven right now about it. I haven't accepted the job yet. But I also just found out I'm 4 weeks pregnant. We were not expecting it to happen so soon. I have not told anyone I'm pregnant and my husband is super excited and so am i. This job is a life changer for sure. But I told my mom about the job offer and she said I should wait to start a family now because I don't want to give them a reason to think I'm unreliable or to find a reason to fire me. (She doesn't know yet) It made me over emotional now and I'm scared that I'll take this job, They will find out I'm pregnant and they will be gunning for me or take it really hard. I don't know what the probationary period is yet and it makes me nervous. I know is illegal but still in in a manufacturing field. Not a lot of females. But I fell in love with the place during my interview and I felt a connection with all of them. ( They had me in a 7 panel interview. ) I loved the professionalism of the team and they were organized etc. A place I can really see myself at.

So do I tell them right away, (I personally like to wait til I'm in the 2nd trimester to be safe, and my job doesn't pose any hazards where I can't work) or do I wait because honestly there is nothing they can do about it. And there's nothing I can do either!

Just wondering what you all think? Or if anyone has ever been in this situation?

Thank you for your help.