Uncle died, leaving an IRA to the estate. Who decides when and how to distribute the funds?

I am the court appointed personal representative of my late uncle's estate. He was only 58 at death so I understand the IRA must be distributed in 5 years or less. He willed the funds to 2 people, but since there were no beneficiaries officially named, it has to go to the estate first. One wants to minimize the tax hit, the other wants the money now. Do I have the power to control the release, or can they dictate the schedule, meaning the money-hungry person can call the shots and screw over the more patient one? Thanks for your help!