When does the *hawl* commence if commercial goods are purchased with currency or other commercial goods less than a *nisab*?

Primary text

If commercial goods are purchased with less than a *nisab* of currency or less than a *nisab* of other commercial goods, the *hawl* commences from the moment its value reaches a full *nisab*, because the completion of a full *hawl* upon a complete *nisab* is a prerequisite for the obligation of Zakat.