Can't get my Head around it

Carrying a green foot bowl to the 'spraying area'

I think I have to increase production of these foot-soaking bowls in order to meet the next deadline after Tuesday's pickup of 32. I'm supposed to have another 85 by the middle of July. I've got an extra 25 already made, some of which have been fired. So that leaves me with 60 to make in the next couple of weeks. I've been making them six at a time, every three days, I think.

See, I make six of the platters (bottom section of foot bowl) one day.
Then I make six bowls (top of foot bowl) the next day and trim the platters.
Then I put them together on the third day, and I usually make another six platters on that same day.

I'm thinking I can make 10 at a time every three days. But that's 18 days. Or is it? I can't get my head around it!