Yes, expose it to light ASAP but be careful with the intensity. CFL lighting is ideal for plants under 2 wks. old as they can be placed very close to the first set of leaves with little risk of causing heat issues or drying out the soil. As the plant matures, lower your light source to help prevent elongation of the main stem ("stretching"). Again, CFL's can be placed as close as 1" away or more. If you have the resources, you can upgrade to a MH/MPS with whatever wattage that you can afford. Good yields can be achieved with light systems with as little as 250W but most regret that choice unless they intend to grow only 1 or 2 plants. Also take into account the size of your grow area or tent as HID lights do generate a significant amount of heat so adequate ventilation should be planned. Even a plant as young as 1 week old can benefit from a small, 8" oscillating fan as it will also help strengthen the main stem and can lessen the chance of overwaterting which is the most common issue with new growers followed closely by overfertilization.