Awarding Bonuses based on hire date in WCP

Summary:

We would like to award bonuses based on the hire date of an employee. By this I mean, getting only 10% of their bonus if they arrived late in the year or 50% if they arrived half way.

Content (required):

Hello experts,

I am putting in place a bonus award system that is pro rated to the time spent in the team. For instance I would like to award 50% of the bonus proposal if an employee arrived in June,

I have a table detailing the exact percentages depending on the month of arrival,

I was just wondering what would be the simplest way to configure this in a WCP,