But to answer your question, I'd try to keep it 20-50%. You need some room for characters, special effects, and post-processing.
The budget always varies from game to game. You often always can't lock down your budgets until you've implemented the whole workload and then started to optimize, cut-back and balance them together... Or you often rely on experience from previous (similar) games to set your starting budgets.
Maybe you want 30% for characters, maybe 10%. Maybe 50% for post, maybe 10% :-/
Often I've seen environments and characters combined at ~25% and post at 50%, but on other games that could be flipped.
What kind of game is it, what camera angles/distances, and what else needs to be drawn?
It's a snowboarding/skiing game. I'll need to draw other static objects like instanced trees, huts, jumps, etc, one main character skinned, probably max of 2 or 3 other close characters plus up to a dozen or other lower detail skinned characters. Draw distance is fairly crucial and needs to be, at times, as far as the eye can see. I've developed a crude dynamic pvs method which I need to redevelop but works ok for now.
I'm currently rendering at an average of around 2ms up to an absolute maximum of 5ms to draw the entire 4096x4096 terrain with all texturing. based on the comments that feels like a pretty good start