Hi, good question. Let us break this into two parts, the lighting (part A) and ventilation (Part B)
Part A. Lighting
Young plants of any kind do not generally require much light in order to initially propagate them. I would strongly recommend keeping the light very far away from the plants, at least until they have developed there first set of three leaves. However other roles do take place in this decision. For instance; what kind of fixture are you using, is there a pane of glass between the light and the plants, and what is the average temperature of your area? All these specifics are very helpful if specific answers is what you are looking for. Plants this age can go anywhere from 18-20 hours a day with the light on, and 6-4 hours a day off.
Part B. Ventilation
Unfortunately there is no right answer. Basically, if it's too hot turn it up, or if it's too cold turn it down. A good rule of thumb however is that you want to be able to move your entire grow rooms volume of air (which you can find by LxWxH) at least once every 2 minutes, although that is fairly low. But after keeping that in mind, just turn the fan up if the temps are higher than 85, or turn it down if they are lower than 78.