By the end of May there will be 3x A330's with the new cabin, that's 75% of the A330 fleet. The question is if they'll do the last one before the summer as well, we'll see.
Either way, keep an eye on
https://scandinaviantraveler.com/se/newcabin and see if the plane you're likely to end up on has been retrofitted by the time of your travel.
On my last 4 TA trips with SK on A330 I've had the new cabin 2 times, in line with expectations.