Either at a trail intersection/ location where deer travel a lot, or next to a food plot. I have most of mine near food plots for two reasons. One b/c deer use the plots they found the TR fairly quick and two, does especially, use these all summer and into the fall, so the TR combined with a new fresh growth creates a very good place to kill some does. The bucks obviously use them two but once they shed their velvet they typically become nocturnal until the rut. By the way, I would pour out a 50 pound bag of corn when you put your rock out. Shouldn't need to put out more corn after that but deer will find corn quickly and then will find and start to use the TR.
By the way, in regards to putting the minerals out in late spring in lieu of just starting now, it's frustrating that my local co-op hasn't figured out that TR's aren't deer attractants for hunting season as much as they provide nutrition during the spring and summer. After 3 years of selling them, they still don't get them in until the first of August. Annoying...