First I would like to say that I like your setup. Though I do have one concern. You mentioned that these were peppers, as a starter box it seems fine but the plant look to be only about 2 or 3 inches apart. As the plants mature this will be a huge problem. You may want to find out how big the plants get when full grown. You will probably need them to be between 2-3 feet apart depending on the type. I had the
bell peppers that I grew (the plants in the upside down 2 litter bottles are peppers) set at 3 feet apart, that gave the plants 1 1/2 feet growing room on both sides.
I beleve the days to maturity are from when they sprout. Plants in Hydroponics generally grow much faster than in soil, but there are many factors that will influence it (light,
nutrients, pH, temp, humidity, type of system, ventilation etc.). When transplanted into the system you probably wont see much of anything in the way of progress for the first week as the plants are just getting used to there new environment. Though it looks like the plants are growing. Just to let you know, you want the
nutrient solution temperature to be continuously between 68 and 72 degree. If the roots are white they are probably healthy, but if they are discolored there is something wrong. Also If the pH level of the nutrient solution is either to high or low the plants wont be able to take up the nutrients they need properly.