One light bulb is not going to do much for you. Do you have a window that receives direct sunlight for part of the day? I would just give the plant natural light and it will grow and flower all on its own. It probably won't get very big though. If you are watering with tap water, add about 1/4 teaspoon of apple cider vinegar to bring the PH down. Wait to water until your plant starts to droop a little. Before adding the water, take note of how heavy the pot feels. Then next time, just water right before the pot feels that light again.
I grew a plant from bagseed on my window sill once years ago. It was in the winter, (less than 12 hours of light) so it began to flower as soon as it was old enough. It flowered just fine despite being in a bathroom where lights were often on at night. In fact, it was some of the best and tastiest peachy weed i've ever smoked. Only produced about 6 grams though.
I am new to growing, and have spent a decent amount of money buying testers and meters and stuff, but you really don't need all that, as I am now learning. Good luck, your plant looks fine, just remember, dryer is better when it comes to your soil. Especially if temps are low.