Identify the proper point to recognize expense for each of the following transactions.

a. Kat Inc. purchases on credit six custom sofas for \(\$ 800\) each in June. Two of the sofas are sold for \(\$ 1,200\) each in June. One of the sofas is sold for \(\$ 1,200\) in July and the remaining three sofas are sold for \(\$ 1,500\) each in August. All sales are for cash. Kat pays its supplier in July.

b. Kira Co. purchases \(\$ 500\) of supplies in January. Half the supplies are used in January with the remaining half used in February.

c. Joseph Co. purchases \(\$ 2,000\) of inventory for cash in September. The entire inventory is sold in November.