20/4 is preferred by some people but it isn't really 'normal'. Most beginning growers do 18/6 from seedling to flower which is about 2 months in total. After that stage you just decrease the lighting to 12/12 and you just wait until the plant shows its sex (hope for a female!) then a month or two later it will start looking like shit to smoke, and when it's 'done' the pistils will start turning brown. I recommend looking at the harvesting and curing section when that time comes. You have ways to go and it will feel like forever till it's finally done.
Unless you're growing a auto flowering strain, If so(which is all in my head that could possibly make sense with this extremely low lumens your plants are getting, it's okay for now, but if they are a normal strain then you're going to need to get many more lights, many many more, I'm going to be using 10 of each in a 34x34 wooden box that's around 3-4 feet tall, adjusting the lights daily as my plants get bigger, Probably even adding 2-4 lights per side of the box, but that will be a little expensive considering how many power stips I'd need, But my first grow will just be with lights above like you are, Just 7 6500k and 3 2700k for the vegging stage, then 7 2700k and 3 6500k for the flowering stage, I wanted 10 of each bulb but that got a little pricey, Either way I suggest you get some more bulbs when they start getting bigger.