Happylab,
My daughter read online that it's good to put a big dog on a leash and tether him/her to something so he/she will just lie down and not be able to jump up. Then the little kittens can explore to big doggy on their own, without fear of being overpowered.
We tried it with our big dog and her new kitten when we were at their house over thanksgiving. It really works. Instead of the kitten hiding all the time, it could come out and sniff the dog, and get used to it on non-threatening terms.