C.P.
What I did was... on day 10 (or 11 in my case), I followed as if I was making starters. Add the ingredients, divide into "4 equal portions,", and then make each of the 4 portions according to the "baking day" directions. You could do it all in one HUGE bowl, but it is a LOT of dough! And, if you do 4 separately, they can be different flavors: 1 cinnamon spice (according to direction), 1 with bananas & nuts, 1 with chocolate pudding and chocolate chips, etc (I figured as long as the dry/wet ingredients are close to the same volume as the directions, it would work). Also, I read somewhere that you can freeze a starter and just bring it back to room temperature before counting "day 1." The dough never really freezes (it feels thick, but still flexible) and I haven't tried baking from that stock, but it's worth a try...