Scotts Rose & Bloom 12-4-8 Fertilizer

Will this actually be of any benefit to me at any point during the growth cycle? If not, no big deal at all as there were 3-pound bags on sale for like $1.75 and I grabbed the last of them for the hell of it whilst getting my other supplies for a grow box. Can I actually use the stuff to my advantage, though? If so, would I start using it during the flowering cycle or at all stages of growing?

if you do decide to use it, use it for veg, or as a nitrogen booster in flowering

It says to just add it to the soil (growing in Scotts potting soil, by the way, sorry). How often?