Joshua and Donna were married. Mya has been their tax preparer for many years. During a meeting with Mya, they disclosed they recently divorced. Mya explained to both of them that a conflict of interest has arisen in their case. They decided to waive the conflict, and both signed separate waivers to continue with Mya as their tax preparer. What is the minimum amount of time that Mya is required to retain the waivers?