I have 5-10 Ca juniper bought it 2 years ago. I let it grow so it could be healthy. I want to change the angle of the tree to informal upright. and reshape it. If I prune now will the tree be ready for repotting in the early Spring . Is spring time the right time of year for major repotting ??
the height of tree is 18" high and 24 " wide
BD
The most important rule is keeping the tree healthy 
If you prune now, I assume you are removing big branches, it will need winter protection if dropping below freezing. What is your location?
Spring is the best time for repots.
The “Right Time” is when the tree is telling or showing you its ready.
Do you have any pics?
Personally, if I was to do any major pruning, I would not repot next spring and let it grow out another season.
Remember that patience is an important part of being a bonsai practitioner/artist 
