Thanks for writing. Your bare-root perennials may bloom this year --- it depends on how large and established the roots you purchased are. But as a general rule, bare-root plants take off and put on good growth the first year.
The best way to plant them is to soak the roots in water for a couple of hours to make sure they're well hydrated. Then dig a planting hole for them and make a cone of soil in the middle. The crown of the perennial should sit on top of the cone, with the roots trailing down the sides of the cone. Then fill the hole with soil, and water well so the roots come into good contact with the soil.
As far as spacing vinca goes... It depends on how quickly you'd like to cover the area. Planting it 8 to 12 inches apart should help give you good coverage relatively quickly.
---Justin, Senior Garden Editor, BHG.com