Winter or early spring are both good times to prune back panicle or Pee Gee hydrangeas (H. panicula) as they flower on new wood. By pruning off weak branches and shortening old branches to 8 inches or so you will have a shrub that makers larger but fewer blooms. This hard pruning is also recommended for hydrangeas such as Lime Light, Annabelle and Incrediball varieties as they also flower on new wood. Not to worry if you skip pruning these hydrangeas as the result will just be plants with more branches and small blooms but it will not affect the health of the hydrangea. The mophead or traditional big leaf hydrangeas (H. macrophylla) do well with no pruning but you can remove the faded flowers in spring by cutting just above a bud as you describe. Most varieties of the mophead hydrangeas flower on two-year-old wood so pruning them back hard before summer would be cutting off all the flower buds.  Hydrangeas are tough shrubs so don't be afraid to experiment with shaping the shrubs by removing wayward branches or worry too much about a specific calendar date for pruning.  Early spring means right before you see daffodils in bloom. The date will be different depending on where you live and the winter weather. Keep growing, Marianne Binetti