Don't change anything.
There is no "Head of household" on a joint return. You are both equal taxpayer-spouses. It does not initially matter what order you enter the two spouses. But once you have filed your first joint return; you should continue to file that way each year, just to keep the IRS from getting confused. In TurboTax, the first person listed in referred to as the "taxpayer" and the 2nd as the "spouse".
