From this moment on...
Can I replace ''moment'' for ''January'' in this sentence?
E.g.: The chemistry class will start from January on. (In French we would say ''à partir de'', in Portuguese we would say ''A partir de''. And what about in English? How do we say that?

Question

From this moment on...
Can I replace ''moment'' for ''January'' in this sentence? 
E.g.: The chemistry class will start from January on. (In French we would say ''à partir de'', in Portuguese we would say ''A partir de''. And what about in English? How do we say that?

Answer

The following are all good options:

The course will start on 10 January.
The course will start in January.
The course will run from 10 January to 9 March.
From 10 January, there will be a class every Tuesday.

You don't need "on" with precise dates and times.  "on" is optional and natural in these phrases:
from then (on)
from this/that moment (on)

Answer

Something like, "The class will start in a moment", if you mean the class will start in a few minutes or so.

Is that what you mean?

Hope this helps

Answer

You can say "from January on", especially if you've established the conversation topic beforehand, but in this context I think it is more natural to say "from January onwards"