how much and when?

hi all,
ok, my plants are on their 6th day of flower at the moment and looking fine.
just one quick question that i cant find an answer to anywhere i look!

i have just bought some 'dr hornbys big bud powder' and i want to know how often i shoudl use it? its 0-10-40 by the way. i looked on the website of the people who make it -advanced nutrients-, on their nutrients calendar but it really made no sense and im growing in soil not hydro.

can anyone help me who has used same product or similar?
cheers guys!