Not real familiar with that mix. If it doesn't have a lot of amendments in it like manure, castings or guano, you can probably start a very mild, 1/4 strength feed at about 2 weeks. If there's a lot of amendments, then wait another week or so, again 1/4 strength and work up from there. Mi5 can be a little nute sensitive, especially in veg, so keep an eye on em.