I felt the same way after my first few days.
You have to make sure you are stretching, another trick is making sure you have a recovery formula within the first 20 minutes after your workout to replenish your muscles, I also eat two slices of fruit like pineapple to give me energy. Also LOTS of water helps as well and sleep.
If the sorness is too unbearable however there is no harm in taking a day off to let your muscles have extra recovery time. This is an intense program and some people have to take it a little slower than other, but if you feel like you can make it through the workout without risk of injury I say go for it.
Just know the sorness is a good thing your body is changing and you will be seeing results before you know it!