Assuming the pup was big enough to be removed from its mother, you could try a 4" pot. Since Bromeliads do not have much of a root system, if any, no need to use a large pot.
Set the pup fairly shallow in soil, keep the soil slightly damp, not moist, because there isn't likely much of a root system to absorb water. If the pup was old enough it should have formed a crown, the tube like center which you can keep water in. This is more important then watering the soil. Keep the pup in bright light, cooler if you can, and do not put it in sunlight that is too strong. Give it time to adjust to being independent. If it wobbles in the pot you can keep it upright by using planting stakes. Locate them at noon, four o'clock and eight o'clock to stabilize it.