Too late for epsom salt spray?

Flowering starts first sign of the flower not the day you flip, takes time for the plant to prepare the hormones, etc, normally it takes 4-5 days after the switch you see the first sign of the flower then you begin counting days., never too l8 to use foliar, the fastest way to remedy deficient nutrient, still looks to be a couple yellow hairs, once your buds stop producing those yellows almost entirely then id start checking your trichomes for cloudiness. Good luck brother Kmurr!