Formal:
* Henceforth
* From this point forward
* Going forward
* Moving forward
* In the future
* Hereafter
Informal:
* From now on
* From this day forward
* From this moment on
* Going forward
* From here out
* In the future
More specific:
* From this time onwards
* From this point in time
* From this moment in time
You can choose the best option based on the context and the tone you want to convey.