[Grammar] For or since

[Sneymarin]

Hello, I would appreciate if someone helped me with the following sentence I read online that has no previous context:

"I've been learning English since 4 months ago"

Someone corrected the above sentence saying that he should write "for 4 months" instead, but I think that it is still correct as you could consider "4 months ago" as the starting point of your action (learning English). That way the use of "since" is justified.
I would like to hear some opinions on wheter you could use "since" that way.

Thank you for your time

 

[tedmc]

Since four months ago is a roundabout way of saying it.
You might as well say "I've been learning English since November 2019".

 

[jutfrank]

It sounds like a learner error. It's a very odd thing to say.

 

[emsr2d2]

As a general rule:

I have been learning English for four months.
(Present perfect continuous + for + duration)

I have been learning English since November.
(Present perfect continuous + since + date or month or year, or combination of them)

I started learning English four months ago.
(Past simple + number of days/months/years + ago)

 

[Tdol]

I would like to hear some opinions on whether you could use "since" that way.

Don't- it is something that native speakers wouldn't say.