As a tax professional here's my opinion... If you are comfortable with your current provider, stick with him/her. This person is familiar with your tax history and how your change in income will effect your tax liability. Knowing this, you can properly plan a payment schedule (either through withholding or estimated payments). I recommend setting up a meeting with your provider to discuss your situation and do some tax planning.
Topics I might suggest... The effect receiving the IRA income will have on the taxability of Social Security (if you are receiving it) and the overall impact it will have on your general income. Will it push long term cap gains into a higher rate? How will the IRA be taxed in your state?
If you are the beneficiary of an estate or trust, speak to the trustee/representative of the estate/trust to find out if you will be receiving a form K-1. This is, basically, the income reporting form from the distribution of the assets of the estate/trust and is reported on the recipients 1040. (Think of it as an estate/trusts W-2.) K-1s are often the last tax form a taxpayer receives. To spare yourself the annoyance and expense of amending your return find out if one will be issued before you file.
Cheers