Had never experienced something like these cicadas 17 years ago. Epic, biblical. Have been waiting ever since. Last few days I've seen a few here and there, but nothing in comparison to what I was expecting. Will this take some time to ramp up?
That said, it also depends on where you are. They can only grow in soil that remained mostly unmolested (no construction) for 17 years. Recently constructed neighborhoods will not have many cicadas. Also, they feed on tree roots, so areas with few trees will have few cicadas.
I can say that I was in Silver Spring, MD for Brood X in the spring of 2004, and for a few days you couldn't take a step without squishing 20 cicadas. Trees looked like you had dropped acid because they were literally covered >50% of their surface area in wiggling cicadas. I started carrying an umbrella because I would be picking them of of myself for a half hour from the mere 20' walk from my car to my front door.
This is how I remember it...