I’m pretty sure the ENTIRE portion of a cash flow hedge is held in OCI until the hedge plays out - so 100% is held until you actually have to pay something out.
Think about this - you’re trying to hedge a 2 year floating rate liability with a swap, with yearly payments. After the first quarter, the company has to report earnings. The value of the swap will have changed, but you’re not sure if its ineffective or effective until you actually have to pay the interest. The fair value of the swap has risen, showing a mark to market adjustment, and the corresponding change is in OCI.
Say the end of the year comes, and the value of the swap has risen to $125. The hedge was effective in offsetting $100 in extra payments due to the floating liability, but now the hedge has caused interest income from the other end of the swap to be over and above the $100 to the tune of $25. $25 income is recognized in earnings. This is a simple example, but hopefully it helps to get the point across (and I have it correct).