nope, some guy on here did a comparison and gained around 4g average extra on topped plants against left alone. too many factors will affect yield, light, nutes, air, care ;)
soak seeds for 20 hours
mine are normally splitting by then in the good old simple method, wet towel, bag abd warmth. you dont need light for germinating initially, and dont thread your plants!!!!
there is no way id be feeding them yet, 3 more sets of main leaves at least, your medium contains enough for 6 weeks grow before becoming deplinished, water only for a week;)