Are you sure that you have pests/bugs? I prefer not to use any type of additives like this unless there is a need to, which you could have (I really can't tell from photos). The general rule of thumb for any type of infestation is to correctly identify the critters and find the best treatment. Neem works well for most, but not all bugs. I would wait until the 2nd set of leaves to get established before I treated them with anything, since seedlings are pretty delicate and easily damaged.