Look at the following post on Instagram:
Career Consulting & Coaching on Instagram: “#lavitadolce and we are in Monday again! The Good news that from this week we will start Saturday #TeaTime together! How does it work? I…”
My question is:
Is this usage of "in" before "Monday" considered correct in formal and standard English?
I think it’s because of “we are.“ Actions happen “on” Monday. But in these cases, the speaker/writer is referring not to an action but to a location on a schedule. In other words, I think the person chose “in” because they were thinking more of a physical location. I believe the proper sentence is "It is Monday" or "Today is Monday".
Anyway, I just need to know what your opinion about this sentence is. I can relate that the sentence is possible in informal English.