The best time to repot Junipers is March/April, up to very early May.
Juniperus Rigida (Tosha) can be repotted later, early to end of May, for they tend to wake up slightly later.
Source: Peter Warren (saruyama.co.uk)
Best time for major branch removal / trimming is spring, just as the tree is coming out of dormancy.
Best time for major wiring / bending (trunk and primary branches) is also spring, or in early fall just as temps cool.
Avoid this type of work in June, July, and August, the bark might separate from the cambium layer and your Shinpaku tree could die as a result. Light pruning is fine, but hard bending is a "no-no".
Best time for foliage removal is during the growing season, sparingly to maintain a clean look on finished trees.
Source: Brian Van Fleet - https://www.bonsainut.com/threads/juniper-bonsai-styling-timing.36703/
In summer, Juniperus may naturally shed its needles in some areas. This is called "Toya" in Japan: the needles turn yellow and fall off. This is a natural process, compare it to pigeons molting their flight feathers, which are shed and then grow new ones.
Scion grafts on junipers are pretty easy to do. We do these about April/May.
Source: https://www.bonsainut.com/threads/juniper-foliage-reduction.71979/post-1239595
Do keep in mind that the preferred time for major pruning work is mid summer. In our time zone that is July.
October is one of the rare time slots where the sap flow on two needle pines is low and the tree can be needle plucked.
You can find an exquisite care guide for Scots Pines in the resources section of bonsainut.com.
(Find the download link to the PDF in the upper right corner of the page)
How to get three flushes in a Hawthorn growing season (mid development)
Source: Tony Tickle 202606
Develop Sekka Hinoki in low unglazed pots (e.g. Japanese terracotta pots)
Repot Sekka Hinoki every two to four years, preferably around May, when the tree shows signs of new growth. An alternative is early fall, when temperatures drop and there is sufficient time for the roots to establish themselves in preparation for winter (6–8 weeks).
Never completely expose the roots. Leave enough of the root ball and the microrhiza at the base of the tree.
For the potting mix, we recommend 3 parts Akadama, 1 part pumice, and 1 part lava rock.
After repotting, place the tree in a bright spot that is not too dry, and protect it from strong winds and frost.
Try to overwinter the Sekka Hinoki in a frost free place. The trees that have overwintered free of frost will grow out faster and ealier than the ones that have been in frosty conditions.