'since very early' is correct and usable in written English.
You can use it to indicate a length of time from which something has been taking place. For example, "I have been watching the sunrise since very early this morning."
We have known each other since very early days.
But then, he hasn't been since very early in the 1990's with the Mets.
Since very early in Putin's tenure, media properties have been steadily redistributed so that they are held in loyal hands.
"I felt the need to do something like this since very early on as an actress," she said.
What do you suggest for someone with a difficult history like mine, who has been chronically anxious since very early childhood?
He has been at the heart of the Ben Ali regime since very early on.
Since a very early age I've been heavily influenced by my father – specifically acting being discussed, not just being a star.
Karroubi later e-mailed me, "Since the very early days after the election, the regime aimed at confining me and controlling my links with my entourage and the members of my party.
Ms. Gillot, 37, said that though she had been choreographing "little shows in the backyard" for family and friends since a very early age, she only started to think about creating her own work when she turned 30.
Despite the narrative now peddled in the West, armed men were present on the streets of Syrian cities and villages since the very early days of the Syrian awakening 18 months ago.
As an Obama supporter since the very early days of the campaign, I think that my mind has been afraid to give voice to my inner disappointment over the president's failure to provide real leadership (and hope) in these difficult times.
