A complete search of the internet has found these results:
effective immediately is the most popular phrase on the web.
"effective immediately" is more formal and official; "effective from now" is less formal and more colloquial.
5,280,000 results on the web
Your inspector general just postponed the investigation effective immediately.
This puts my retirement effective immediately.
Holly will begin her trial period effective immediately.
You're relieved of duty, effective immediately.
I resign as chairman, effective immediately.
Liaison duties are discontinued, effective immediately.
You're hereby placed on administrative leave, effective immediately.
I'd like to tender my resignation, effective immediately.
I will announce Jordan's departure from my staff effective immediately.
We're cutting our losses, the program's being terminated effective immediately.
So for sites classified strategic 2 or higher, we are reactivating analog alert systems effective immediately.
Effective immediately, we will no longer have lunch outdoors.
117,000 results on the web
Termination without pension, effective 10 days from now.
The universal vocation of the WTO will therefore be reinforced and the discussions on the ways of making its operation more effective will from now on be an absolutely essential exercise.
The law there is pretty effective from now on I think.
Dear Gillian, only an amateur, of course, but very effective now and then.
Lastly, the Commission turns to economic governance, now possible thanks to the work of the Eurogroup, which has been even more effective now that it can count on a permanent president.
I think there are more effective meds now.
The effective age from now: 85.
I believe the words she used were "effective from now."