Juniper sold as bonsai are propagated. This means that its root system is quite small even by bonsai standards.
Plan on growing him outdoors in afternoon shade ( in MS) for the forseable future.
He will be a year or more away from much pinching-pruning.
Plan on a fertilizer application, May to October every other week, use a soluble fert at about 1/4 the recommended strength.
Indoor heating and air conditioning will suck all the juice out of a juniper quicker'n Bella Lugosi inna vampire movie.