Okey dokey, you're on the right track. The fan is good. Patience is good. It is easy to kill seedlings by loving them too much!
Hold off on the ferts and topping.
If you choose to pinch, wait until the plant has at least 4-5 pairs of true leaves.
If you want to start fertilizing now, or soon, start off with 1/4 strength grow nutes, plus superthrive if you have it.
Your temperature should be okay. 88 is a tad high, if you can drop it to 70-80 you'll be a bit better off.
Finally, save the HPS for flowering. The light spectrum you want at this growth stage can be CHEAPLY acheived with compact flourescents.
Keep posting pics!