Code J is correct. By itself, having the Roth IRA for 5 years is insufficient. [Edit] Provided that you meet the IRS definition of "disabled," your distribution is a tax-free qualified distribution.
Reporting this distribution properly using TurboTax requires using forms mode of the CD/download version of TurboTax. You must manually mark the box labeled "If box 7 code is J or T, check if a qualified distribution" on TurboTax's 1099-R Form for this distribution. Switch to forms mode, open the 1099-R form, then mark this box.
