Where to prune young plum tree

HI
I have a young plum tree around 3 years old. I have outlined it's branches in the attached photo. I am reasonably happy with it's shape however branch 1 and 2 are going into and over the fence. I am looking for some advice on the following:
Where should I prune branch 1 and 2?
Are there any other branches that I should look to prune?
What time of the year should I prune?
There are two photos (Where to cut). Should I look to cut over a bud with leaves on or one without?
Thank you
Iain

 

Hi ijolly4

There are lots of things to consider when pruning fruit trees including why you want to prune (for form or fruit), when, how and by how much. May I suggest getting the book 'The Pruning Specialist' by David Squire. It should tell you everything you need to know about pruning a plum tree.