prepositions - How to use "by" and "until" in these specific contexts?

• I've watched 10 movies until now.


• He should have been here by now


• I think in the first sentence, "by" doesn't work and using it will not be idiomatic. This applies to the using "until" in later sentence too. For me using "until" will not be be a correct usage. Instead the "until" in the first sentence and "by" in the second sentence fit the best. Am I right?