By ' still use the car' until the dryer comes in... I assume you mean NOT activating the compressor...either by leaving off the belt..or not hooking up the electrical wires to it ?
I would not allow that oil in the dryer to be forced into the system. It will be pushed to the evaporator ( if the back pressure does not blow your condenser ) ...and it is usually not even flushed... so in changing oils several times you are risking mixing the oils bigtime.... no one that I know of suggests that is good. Remember, the oil circulates around the system by being mixed in the refrigerant vapor... particularly for our non sump R4 compressors... if the oils mix and gell up enough then your compressor has no lubricant to work with.