I am retired, working part time. My wife is also retired but self employed. If we move $ to a traditional IRA to reduce taxes, when can we withdraw it without penalty?

We both draw social security and I get a small pension.  I would like to open a new IRA for each of us. The money is in a money market account right now.  If I do that, is there a minimum amount of time we must keep it in the IRA before we can pull it back out?