How to say "It has been (time) since...."


I came across this sentence in my grammar dictionary "アメリカに来てから今日で三年になる",
which is translated as "It's been 3 years since I came to America". Is this
the standard way of expressing "It's been... since..." ? Is "今日で" redundant or
necessary?

I would be very grateful if you could provide some example sentences for me to
examine. Thanks




>   1. Is this the standard way of expressing "It's been... since..."?
>

Yes. Alternatively, you can simply say アメリカに来てから今日で3年だ/です. You can find
hundreds of examples
[here](https://ejje.weblio.jp/sentence/content/been+years+since).

>   2. Is "今日で" redundant or necessary?
>

～で is optional if the reference time point is today, this month, etc.
Unsurprisingly, you can specify another reference time point like so:

> アメリカに来てから来月で3年になる。  
>  Next month, it will be 3 years since I came to America.

