I interpreted Jaldoa taking a roundabout route to get back to his tree. It was that route which I wanted to intercept. If he sprung directly away from it, then rolled diagonally forwards, that's still an obtuse arc; I figured the border of Jaldoa's view would be a fair few yards, implying a several-second travel. 

Chester doesn't need the coins to make a Vertex. Once he's sighted what they're being attached to, he can summon them quickly. The limit is that he can't attach them to objects that move, unless they came out of his hand. (ricochets won't work either, he needs an uninfluenced measure of its velocity. I don't think I specified that in the CS.) 

Made the first Vertex as Jaldoa escaped. Equipping his gadget, a couple seconds. Glimpsing Jaldoa through the trees, another five maybe, since he only had to determine if he was left, right or away. The second Vertex would be a fraction after that, so an interrupt seemed reasonable in all. Apologies if I overestimated?