ladies, I need advice about my work situation!

I recently just moved back home from California to Las Vegas leaving my job of 8 months behind. Today I had an interview for another food place & I got the job. It opens in three weeks, but I am 18 weeks pregnant tomorrow and I didn't tell them in fear that it would not be hired if I was pregnant, but now I am feeling guilty & dishonest & im not sure when I should tell them, or how. I was thinking maybe just keep it to myself until someone asks or would it be better to tell them?? Any advice would be appreciated!!!