How can I count SPI clocks in Raspberry Pi?

I am interfacing MCP3208 with Raspberry Pi3 using SPI communication. This ADC completes one conversion in 24 clock cycles. In my data acquisition system, how can I count these 24 SPI clock pulses so as to generate a busy signal till that time? The ADC should not accept any incoming signal during that conversion period. Can anybody suggest me some idea and the corresponding C code?