my first grow was in coir, dont worry , just know your shit, buy some PH down and up, only use one per a solution, which means no going to far up or down and then trying to correct it
also your coir likes to live at 5.6 to 6.2PH let your nutrient solution sit for a 30 min or so to mix correctly before using PH adjusters
i think coir as long as its wet is the most forgiving medium to use, hands down and i have done most, and wet doesnt mean soaked, wet mean like 30-60% water volume is neccesary for constant intake of nutrients and give your plants a tea or tonic day with no ferts once a week, i got a buddy that goes 3 days feeding and 1 day water tonic, then start over
oh ya and i dont flush ever . . . .and i mean it never, use products like sea green , kelp, and myco products with molasses or beat extract to make your root zone a machine at devouring waste or chelating the nutrients your bennies create, and i do not need to flush during cycle, just at the end of flowering and i normally can stop giving my plants ferts for 2-3 weeks depending on strain, my product comes out smooth and flavorful