okay well you do not need the light on until you see a sprout.. how is light gonna help the soil?
second you can get by with miracle grow i guess but im sure your going to run into problems that u cant seem to figure out. your better off with a soilless mix but i will take into consideration u have already started so ill try to help u from there..
you dont need to water it much!
u should have cut drainage holes in the bottom of the soda bottle
then u go ahead and give the container/soil a good watering. leave it unwatered for a couple days ( the sprout's tap root will grow larger if it has to LOOK for the water instead of being force fed it)
but in future grows try to avoid planting seeds directly into soil.. if you germinate them u have a higher success rate and are able to determine which seeds have popped and which are non viable... in time u will become very familiar with these routines..
to germinate :
just take a paper towel, moisten it, put your seeds on it, seal it in a plastic ziploc bag (remove excess air)
then place that in a dark, warm place (on top of a refrigerator)
in a day or 2 u should see the begining of a root.. as soon as u see the root, take it and place it about half of an inch into your soil (poke a small hole with your finger) then cover it loosely with soil... this soil should have been watered before planting the seed ( do not water again until the top inch or so of the soil feels dry when u stick ur finger down into it..
hope this helps