Frances, God bless you for this confession. It will give you more graces than if you had done nothing wrong. Felix culpa !
Oh, that's a plan: you can go to confession later -- and then not
only would you get to do the sin in the first place, "it will give you
more graces that if you had done nothing wrong" to begin with!
One problem with that: in order for your confession to be VALID,
you will have to confess that you PLANNED on doing this evil thing
and then going to confession later. If that is the truth, and you
don't mention it to your confessor, even if he absolves you, your
sin is not forgiven
because the confession isn't valid, due to the
fact that you failed to tell the priest that you had planned on
confessing the sin later before you committed the sin in the first