Morning sickness typically peaks in the first trimester, starting around week 6. My doctor allowed me to do gentle morning walks which really helped ease the nausea.
Usually first trimester, but if you have severe vomiting and can't even keep water down, please contact your doctor immediately. You don't want to get dehydrated.
For me, it started right around week 6 and lasted until week 14, it was so exhausting. I feel your pain, but hang in there, it gets so much better after delivery!
With my PCOS history, my hormones were already unbalanced and nausea hit me quite early in week 5. Every pregnancy is different, so dont worry if yours starts earlier or later.