Your foreign worker quota is calculated based on the latest 3-month average number of local employees in your company.
The number of local employees is based on the CPF contribution you have made to them, under the same company CPF account.
If you pay your employees’ July CPF contributions after 14 July, the quota will be calculated based on your number of local employees in May, June, July’s CPF contributions. This quota will only be updated in September.
However if you want the quota to be updated earlier, i.e. August, you should make your CPF contributions by 14 July.