Usage patterns
かねて〈動詞〉ているto have long been doing/planning something
The overseas business trip I had been planning for some time finally happened.
かねての〈事〉a long-standing (plan, wish, concern, etc.)
The long-standing concern finally became reality.
かねてご案内の通りas previously announced/informed (formal notice)
As previously announced, we will revise our prices starting next month.
Expressions
かねてからfor some time now; for quite a while; already かねてよりpreviously; already; for some time