called today again to Czech delta (AF/KL call centre). Got a cancelled flight for next week, they told me they can give me any flights within 30days or I have to have the same booking classes + same routing (airports) and I can move it to anytime. Moved to April for now. Highly recommend.
(keep in mind you will get your Delta ticket changed into KL ticket stock (074)!! (as czech delta cant ticket it as delta stock)