Ec can range from 0.3 to 1.8 before problems will occur, the light mix is around 1.2 giving it the flexibility of being able to add a little extra salts if you wanted in first couple weeks but it's generally not recommended, don't want the ec too high as it's generally recommended to begin a seedling on 0.3 ec but absolutely not necessary although running a seedling at 1.8 would cause unwanted water stress early in life. Once she has her structure and hits vegetative stage, start feeding normally.
Best advice to new growers would be to grab yourself a ec metre for soil and keep tabs after each watering, once ec gets low, reapply, always saturating your pot to 5-10% run off.
Water water water till ec tells you too, if it gets a little high, flush and reset.
Gluck