My experience was Fluoxetine was that things got worse before it got better, and things didn't really turn around until about week 7.
I was offered Diazepam to help me through the first few weeks. I am glad you are seeing your doctor on Wednesday. Until then, when you feel very anxious, try telling yourself that how you feel is 'just side effects'. I also used Rescue Remedy which you can get from pretty much any pharmacy, just check with the pharmacist about interactions with whatever medications you are taking.