Late winter is thenorm because of risk of dieback in hot seasons.

You might try taking off little shoots on the offending branch ,now ,to let in some light. I wouldn't risk big cuts right now.

Readers digest Illustrated Guide to gardening has a good article on peach pruning.

Also, call your local county ag fellow and ask him if it would be detrimental to cut now being all you want to accomplish is getting rid of a bad branch.

Here is TAMU info on stone fruit trees, trimming, etc.

Here is a link that might be useful: TAmu peach info

Can you just train the branch to go out at the proper angle?

Wish we had noticed that one main branch growing more horizontally sooner and we could have trained it but it's too large now to attempt that. Looks like it may be late summer before attempting any pruning.