you should really get yuorself a copy of thr Yeast book by Chris White and Jamil Zainashelf, they describe commercial propogation of yeast. You basically follow the 10x rule. This from the book from starting from a slant, using degrees Plato (P), the first part done in the lab
slant - 10ml wort at 8P at 25C 24hrs; 100ml wort at 8P 25C 24hrs; 1000ml wort 12-16P 22C 24-48hrs; 10L wort 12-16P 22C 48hrs; it is then transferred to the brewery to continue, which usually lasts 5 days
I'd PM Unclepumple and get some advise, he is brewing commercially.