I actually think you get more action in the end if you take the stun off the end of it. Here are your actions in the two ways of doing a Stun Relief I spell (F= full, P=partial, S=stunned/none):
Do as Spectre and KPadish do it:
Round 1, 2, 3:
P, S, S
Do as I do it:
Round 1, 2, 3:
S, S, F
As you can see, you get more action if you take the stun off the end rather than off the current round. This is because if you take it off the current round, your activity for the current round is restricted by the % you had to use to cast the spell. So you get one partial round of action right now (25% if you use the core rules, 50% if you use the option that instant spells only cost 50% action) vs. getting a full round later.
Either way works, I just prefer the latter, especially in RMU (where there is no more Stunned Maneuvering, so the stun relief is clearly superior). You might say that a partial round of activity now is better than a full round later, so I could see either being argued as the most beneficial for players. But I think the intent was the latter.