Slit decal, apply just a little Solavaset, see it wick under the decal, watch the reaction, let it settle a bit. If the decal starts to shrivel a little, that’s OK. If it shrivels a lot, then that’s too much Solvaset. Remember, go slow.
Different brands of decals react differently - some will take it well and suck down onto the model, others will literally melt, others (I think the thick offset litho ones) won’t react at all. Test-test-test.