You don't have to expect it at all. Not everyone gets it. That said, I think it's most common between about 4-14 weeks gestation (of course there are exceptions -- some people have it the whole time and others are like me, and never have it at all).
Don't wish for it! I got it at about 5 weeks I guess, but I didn't know I was pregnant yet and just thought it was my usual nausea. I am 16 weeks now and it has gone away some, but not completly. Good luck to you with your pregnancy!
I thought I would be lucky but around 6w5d certin foods strted tuning my stomache and it slowly got worse. I can count on one hand the actual puking amount but it was the nausea and dry heaves that I am getting. I am now 10w3d and still gaggy when smells hit me and the though of certin foods make me gag.
I thought I was going to be lucky and not get it, but then in my 9th week (from LMP) I started getting this carsick feeling - actually first happened while I was in the doctor's office for my first visit, so I thought maybe it was just nerves - but it didn't go away. The gag thing kicked in a day or so after that. I'm in the my 13th week now, and today's actually the first day that I've felt good enough to start exercising again, but it's still there a bit, lurking in the background. It's been sort of an all-through-the-day carsick kind of feeling - haven't had to run to the toilet to puke, but have definitely felt 'ill'. And lots of gagging when I brush my teeth, or cough up phlegm, or try to take my multi-vitamin. Have actually had to skip the vitamin here and there cause I simply couldn't get it down...but I don't feel too bad, cause I'm eating really healthy. Good luck!