With a nylon/wool blend, IC's approach is probably the better one. Wet the item in room temperature water, pin it out to size, let it dry in place.
If you're blocking with an iron, you need to be very careful with nylon fibres as the iron can melt them a bit even at cool-ish temperatures. The knit item will have shiny flat patches wherever the fibres were fused. That said, it can be done if you're careful.
Use a thin cloth like a handkerchief. Soak it in cold water and then wring it out so that it's not dripping, but it is wet. Press the iron down and hold it in place until you start to see steam rising from the thin cloth. Repeat the until the entire item has been blocked. difficult child's cloth might not have been saturated enough, and the iron might have been a bit too cool. Go gently with raising the temperature -- about half a step at a time if your iron does that.
To be on the safe side, I would go with IC's method.
Hope this helps,
Trinity