Sometimes I start a sentence saying "Just for information...".
Is this correct?
I use also to begin a sentence with ""Maybe you can help me a bit...", but I would like to know something more about this specific way of introducing a sentence.
Sometimes I also tend to use ""Just for my information..." or "For my information..."
"Just for information, do you know which book should we read at home for next week?"
I have never heard or seen "just for my information" used.
That phrase is usually used to give info to another person:
Just for your information, use the back door when entering the building.
Just for your information, they are no longer dating.
You might try;
Just so I'm clear, what is the assignment in math?