Actually, a few things are not clear to me from your post. However, at a glance, I would like to advise you that it's better to document the policy first. Giving 25 days' salary will not be an issue in my view, as you are all starting a new system, and this will only be for the first month.
Employee Salary Concerns
The main problem lies with employees who will not receive a salary for one month (30 days). In that case, 5 days' salary will be less, and for junior staff, even one day's pay matters. Therefore, it is always better to take the employees into confidence and inform them in advance so that there will be no dissatisfaction after receiving their salary.
I hope a few things are clearer to you.
Best regards,
Regards