That will take some getting used to. Several weeks is a possibility. When I started it, I was on 200mg XR at night and that took a long time before I was ok to drive, almost a month, but by the end of the month, my doctor upped it again to 400 and changed to immediate release. I stayed on that for a long time.
Seroquel can be wonderful, but it does take getting used to. I know a guy that took it like you're describing and after about 3 weeks he "broke through" and became an extremely well adjusted guy all at once. It lasted for 7 years almost.
My daughter is taking XR twice a day. She says it's helping but really thought she was coming unglued at first.
Hang in there. Call your Dr if needed. If you're really not in control, you know where to go.