Word Stress Within a Phrase

[zoltankr]

Hi, when I pronounce the phrase "I'll be home by ten" it can have different meanings based on the stress.

Let's say I pronounce the phrase "I'll be home by ten" at five o'clock.
I want to communicate that I will arrive home at 6, 7, 8, 9, or 10 but not 10:05 or later. If I want this meaning, I think it's only important to stress the word "by" in the whole phrase. Am I right?

[aɪl bɪ hoʊm ˈbaɪ tɛn]

I know that "by" is a preposition and usually we don't stress function words but in the phrase above I think the stress needed. Am I right?

I would like to have a feedback from a native speaker. Thank you for your time.

[panini]

No, it is distinctly unnatural to stress "by". If you want to contrast "10" with some other value, you can emphasize "10". The only way to put emphasis on a preposition is if you are contrasting "by" with some other preposition, like "after", and then you wouldn't use "by" since it's vague -- instead you'd say "before" or "no later than".

[zoltankr]

Does that phrase have a natural stress then? or should I slightly stress the content word "home"?

[panini]

The accents should go on "home" and "10", and "10" should be subordinate to "home".