Buds continually need to be reduced to two as they.
Pruning of branches is nearly always carried out when the trees' growth slows down in late Autumn through to Spring to avoid excessive sap-loss.
When pruning in Winter it is always best to leave a small stub rather than cut back close to the trunk. Combined with pruning of the current years growth on a Pine bonsai, needle-plucking is also the best way of prompting backbudding as well as controlling the height and width of a pine bonsai. Timing is important; it should be carried out after the new growth of the current growing-season has extended, from mid-July (late-Summer) until Autumn.
Nov 05, Branch pruning for most pines, late winter to early spring is the best time. Mugo Pines, the best time is late summer. For my area that means August to early Septembe. Also for mugos, you want to leave a stub for a year or so to prevent trunk death on that side. I.