“from now” vs “from now on”

In scientific writing, I sometimes introduce variables in the introduction section as follows:

The number of gizmos is expoinential in the number of hickeys (for which we write ℎ from now on). […] We ask ourselves how the following quantities grow with ℎ: the number of doodahs, thingums, and whatsits.

I'm often extremely tight on space, so, I wonder whether I could shorten this to

The number of gizmos is expoinential in the number of hickeys (for which we write ℎ from now). […] We ask ourselves how the following quantities grow with ℎ: the number of doodahs, thingums, and whatsits.

Is this shortening (“from now on” → “from now”) possible without a change in the meaning? Would the short version sound normal or unusual?

I welcome answers from mathematicians who are native AmE speakers and have an excellent command of English.

Solution 1:

You could just say

(which we represent by h),

which is slightly shorter and more formal than either of your suggestions.

There's no need for "from now on" at all.