u/AlternativeCan8810

In a scenario where I have 12 runes available, and I decide to play the 4th spell with energy cost 4 or more, am I allowed to wait for the spell to resolve, recycle 4 runes to float 4 power, and then activate the Jhin legend ability to channel 4 runes? This way, it would allow me to have 4 power floating to use for my other spells, that I would otherwise not have. Just wondering if this would this be a legal timing because it seems like the legend ability would trigger immediately, so I'm not sure if I can recycle in reaction to the trigger. Any clarification on this?