Thank you for the questions.

Pruning can be done during the dormant season in winter, but it's important to consider the specific needs and characteristics of each plant. Mild winter weather might indeed provide an opportunity for pruning earlier than usual. However, it's crucial to be cautious, especially with certain plants like apple trees, which are susceptible to diseases that can be spread more easily when pruned during wet conditions.

Here are some general guidelines for each type of plant you mentioned:

1. **Apple Trees:**
Pruning apple trees during winter dormancy is common. It's generally recommended to prune before the trees break dormancy in early spring. Aim for late winter, ideally before new growth starts. Selective pruning can help improve the structure and encourage better fruit production. Be sure to remove dead, diseased, or crossing branches.  This article/video
link may be helpful: https://extension.umn.edu/yard-and-garden-news/nows-time-prune-apple-trees

2. **White Pine:**
White pines are usually pruned to shape them and remove any dead or diseased branches. Late winter or early spring is a suitable time for this. Avoid heavy pruning, especially on older growth, as pines have limited ability to produce new buds on old wood.

3. **Viburnum:**
Viburnums can tolerate pruning well. Late winter or early spring is a good time for major pruning. Remove dead or crossing branches and shape the plant as needed. Keep in mind that pruning may impact flowering, so adjust your timing accordingly.

4. **Hemlock:**
Light shearing back of hemlocks can be done in late winter or early spring. Be cautious not to remove too much of the green growth, as hemlocks may have limited ability to regenerate foliage on older wood.

Info on general tree pruning: https://extension.umn.edu/planting-and-growing-guides/pruning-trees-and-shrubs

Considering the mild winter weather, you might be able to start your pruning tasks a bit earlier than usual, but make sure the weather conditions are dry to minimize the risk of disease transmission. Always use sharp, clean tools to make clean cuts and reduce the chances of introducing pathogens.

Please reach out if you have further questions.