Proper usage of "since" and "from" with regard to duration of time

When you returned, I had been at home since 10 minutes.

When you returned, I had been at home from 5 minutes.

In such sentences, is it correct to use since or from? When since is used?

This is an area which often gives difficulty between English and other European languages.

over a period: "for", "I have been working for two hours" (In some cases you can omit the 'for', eg "I have been waiting two hours")
from a point: "since": "I have been working since 12"

"From" is unusual here: I think it is only used to give emphasis to the starting point, and notice that it would take a simple past continous, not a perfect continuous: "I was waiting here from 12 o'clock!"

A difficulty that French and German speakers often have is that they want to say "I am here since ... ", which is never idiomatic in English. There is one instance of this that actually does cause confusion some times: when an English speaker asks "How long are you here?" they are asking about the future, but a French or German speaker will often misunderstand that as about the past (i.e. "How long have you been here?").

Both are wrong. You use since when talking about a specific point in time. (I suppose you could use from in this case as well, but I haven't seen it in actual American usage.) For example:

When you returned, I had been home since 3:00.

When talking about a duration, for is used:

When you returned, I had been home for 10 minutes.

Both seem awkward.

I would write

When you returned I had been home for 10 minutes.

I won't say since and from in the example sentence provided because since indicates a point of time, whereas from denotes time from starting to end. Let's see in this example: