[Harry Red]

From what I understand, the small round leaves that appear first are the initial source of food for seedlings.

Big Bloom (0.01-0.3-0.7) is all organic and a good source of micro-nutes so giving them a dose of that at the beginning shouldn't hurt anything. FF recommends using Big Bloom all the way through both veg and flowering to help supply trace elements. I typically wouldn't really consider something with only 0.3 P a flowering nute.