class 4 + 2 nic

Sir i wanted to confirm one thing, unless we are calculating employee nic we do not have to time apportion the annual thresholds of 8632 and 50000, like when calculating class 4 NIC- Sole trader commences trading on 1 december 2019 and makes a period of account to 31 july then class 4 nic will be ( profit x4/8 – 8632)x9%, right sir???

and class 2 nic will be 17weeks x 3

Thank you!