I think everyone is different I had bars in my first week and still lost well... I was in ketosis in 3 days having 3 shakes and a bar. I was advised it may slow me down but ultimately it was my decision, I wanted the bars for easiness sake.
just in case you thought you were somehwere else - you have posted this in the LL forum, yet you addressed CDers. Just inc ase you wanted to post it there too.