They might not ever. There's no rule you had to have any symptoms, and even if you do there's no time they have to start by.
i started getting cravings around 2 weeks ago. i'm 17 weeks now.
I'm 33 weeks and 3 days and I haven't had any cravings and I haven't long got a little belly that's not even noticeable..every woman and pregnancy is different love so not all you read will happen to you love xxx