hi ladies - i can answer both your questions for you being a sufferer of thrush for MANY years
Anytime i took diflucan we would try to wait at least 7 days for the infection to have cleared up - it seems like ages but tbh its better than passing it back & forth between you (OH sometimes wouldnt have any symptoms) as this happened loads to me.. Sometimes he has to use the canestan aswell - poor bugger lol
As for the canestan cream - yeah its perfectly safe to use during pregnancy, i used it loads during my last 2 pregnancies!!
Hope you both feeling better soon coz i know what its like to be bothered with this

x