Your plants will mostly just hybernate with that kind of light. It's good to have low light during the first week or two, but now it's time to turn on the real light, or they won't grow much at all. When you switch to real light keep it a few feet away the first day, then slowly begin to move it closer, until it is as close as the plants can stand. This could be one inch, or twelve, depending on what light you are using, your ventalation, humidity, etc.

The yellowing on those two first leaves is completly normal. If the other two plants are not showing signs of distress, then everything is probably set up close enough to correct (except the light).

Good luck and keep us posted.