Advice on cannabis plant

Probably stunted from over watering for one. You can get away with CLF lights during veg, but flowering I recommend hps or led.
Need to add perlite when you get a bigger container.
My current 6 Jock Horror Autos, coco coir grow.

 

That looks like some low quality soil. I can see sticks and bark in it everywhere. You won't see near that much in a properly made soil. Your plant looks ok. At least it's still healthy.

I'm not a huge fan of bag soils in general. I don't like guessing on how much nutrients they have or when to start feeding. As up in smoke mentioned you need some perlite. Perlite is amazing stuff and I won't grow without copious quantities in my medium no matter what I use 10-20% perlite. It boosts drainage and absorbs water. It lets the water out when the plant needs it to keep the plant moist but the medium relatively dry allowing feeding and aerating at the same time. I like having all the control and using a hydroponic medium like promix.

It's highly available these days at homedepot, truevalue, and walmart.com. Sunshine promix 4 is my preferred variety. I use precision perlite course at 15-20% of my mix.

I always finish in fabric pots. Those combined with lots of perlite gives you lots of oxygen to the roots and aids in rapid growth and feed rate. 5-7 gallon for finish in most personal sized gardens.

There's lots of nutrient lines out there but only a few you can grow cannabis start to finish with one bottle. One that does work is General Hydroponics floranova bloom. You can feed a plant it's whole life cycle with just that bottle increasing the amount as the plant gets older and further in the grow cycle. A ph testing method and a routine that can put you in the range of 6.0 every time you feed. I start plants on 1-2ml's gallon, veg with 3-4ml's gallon, and bloom with 5-6. It's about $20 a quart.

 

Like Tbone said above, the soil doesn't look like it's very good quality and there is no perlite. If you want fast growth, perlite is a must - it aerates the soil and provides oxygen to the root zone - the key to fast growth. The pic is of 3 week old plants for your comparison.

 

Get some better soil. It"s worth the money to buy the prepared grow soils since they're specifically designed for these plants. Drainage is a big deal and that soil looks like it will hold too much water. Have to give these plants defined wet/dry cycles to stay healthy...meaning, NEVER water a plant until you can lift the container and feel NO WEIGHT. Any weight you feel is water still in the soil. They don't like the roots sitting in wet soil constantly. Your plant is stretching because your lamp is too far away from the plant. When they are seedlings, they need more heat than light. But once they've put down a root system and have started putting on new growth at a good clip, you can pour the light to them. We veg under CFLs 24/0 for 10 weeks. Keep light and plant as close as possible without danger of light burn (LEDs burn hotter to MJ plants than other forms of lighting, so bring it down carefully) to get less stretch and more bush. If you need height on your plant, pull the lamp away from it. But don't hang your lamp next to the ceiling and put your plants on the floor unless you want incredibly long stems. Learn to use your light to your advantage. No baby needs nutes. We don't start infants out on steak and potatoes. Your plant needs to mature a good bit before you start using nutes. Know this: Nutes FEED plants but LIGHT grows plants. If you use a good quality soil, you do not need tons and tons of chemicals poured into your plants to get them to grow. What you do have to have is good quality lighting. Best of luck. TWW

 

Putting it on top will serve no purpose. When you transplant, put it in a mixture of good soil and perlite.