It is instinctive for kittens to use the litter box by smell. They are typically litter trained by 5 weeks. However, it is important in a new home to have the litter box close and very accessible. If at a later time, you wish to move it, just be sure they are put in it and know where to go. Put the baby in the box periodically. If there is an accident, do not allow them to repeat and they need to be in a restrictive area such as a bathroom. If they are allowed to go to the same place where there was an accident, it can become a learned behavior even if you do everything to eliminate the odor. This rarely happens, and if it does, please call me and I will assist with a plan.