Pruning is very important for developing a healthy bush. However, after planting pruning depends on the variety and the age of the plant you are planting.

If you are planting 2-3 year old plants, you need to remove the central shoot because it will not allow the plant to develop more shoots from the crown. You need to remove all aged (gray color) wood and all weak shoots, or shoots that touch the ground. You can prune immediately after planting or wait until next year after the plants have been winterized and have developed their root system. 

If you are planting 1-year old plants wait untile the plants are established. In a normal planting it is not uncommun to see plant mortality of 10-15 %. By delaying the pruning you give the plants time to develop a good root system and the 2^nd year you can prune them.

Regarding the question of use of Sevin, blueberry plants produce fruit afteter the 2-3^rd year of planting. If you are just planting you do not need to worry about spraying, yet. But Sevin is not a good insecticide for any of the pests that attack blueberries. Inscticides are especific for a particular pest they are not something that you need to apply if you do not have a pest problem. If you ever get a pest in your bushes call MSU Extension por assistance.

However, from your questions it seems to me that you are not a blueberry grower but a homeowner with a few plants. If that is the case, you may get more assistance from the MSU Master Gardener program by calling the Hotline at <personal data hidden> or visit www.migarden.msu.edu for more questions or assistace