what about HQs? or protection? or ships? or air forces?100 x 400 officer divisions = 40000 officers needed, requiring about 36000 more from the starting amount. Under service by requirement 1 leadership = 6 officers per day, three year draft = 5 officers per day.
China starts with about 15 leadership, united it has around 25 leadership.
36000/(15*5) = 480 days to reach 100% officer ratio as standard Nat China and three year draft.
36000/(25*6) = 240 days to reach 100% officer ratio as united China and service by requirement.
As for supply cost, INF/INF/ART/ART is as good or more effective in supply cost per Soft Attack than standard infantry.