The IRA custodian needs to be notified to set up an IRA that will be titled something like "Jane Doe as beneficiary of Mary Smith". I am not aware of a specific time frame, but Jane can't take any withdrawals until the ownership is changed, and Jane's tax obligations are not changed or delayed if she delays the name change.
Since Mary was past her RMD beginning date, Jane is required to take RMDs based on Jane's life expectancy, starting in 2024. Jane can, of course, withdraw more than the minimum amount if she wants to. Jane is also required to completely empty the account within 10 years. (In other words, both the RMD and 10 year closeout rules apply.) Note that the RMD rule is not currently written in IRS publication 590-B, because the IRS has not finalized the rule. The IRS will not penalize anyone who failed to take an RMD in 2023 or earlier, but they expect to enforce the rule beginning in 2024.
While Jane could wait 9 years to withdraw most of the money (after taking the RMDs) that could result in a high tax burden in the 10th year. Jane, her spouse, and their financial advisors may want to look over all the facts and circumstances to plan the best way to manage this money.
