The Evocation specialist wizard's overchannel ability says:

When you cast a wizard spell of 5th level or lower that deals damage, you can deal maximum damage with your spell.

Does the "that deals damage" clause mean the wizard can decide to overchannel once they are sure the spell is going to deal some damage? i.e., that it is not counterspelled or evaded by a successful save, etc.

(This would be similar to paladins being able to choose to apply smite damage after they know they have hit, so this kind of post-hoc add on is not unprecedented.)