I also think it's quite possible he was not hunting for a victim that day at all, but he saw them at whatever point and for whatever reason wanted to engage them. I don't think it necessarily took planning to corner them there, either, but I bet he knew he could if they crossed the bridge, because he was familiar.
This is JMO, and it's only me guessing at random, but I don't think he planned or prepared a kill site, hung trail cams, scoped out the trail for victims, stuffed his jacket full of fantasy items, or any other pre-mediated activity. I don't know why I think that, but I do. There's just as good a chance he did any of those things as not, but I can't see it.
I think in the space between the south end of the bridge and the creek, he got control and started his attack. I'm guessing L's shoe and phone and whatever else might have been lost during a struggle on the south side and whatever caused him to decide to take them across the creek was maybe an impulsive move to get them all out of sight. Or the girls ran that way. I don't know. If he left signatures, I think they were likely manifestations of his heightened state in that moment, and if things were "odd" it's because he's odd in his mentality, anyway. JMO