What is the best idiomatic way to point out an approximate time that happened during a month?
For example:
During the first semester he was basically passive and just observing things. During the second semester, however, there was a small change in him somewhere in April when he began participating in small discussions in class and became more active in team competitions.
"sometime in April" ?
"somewhere during April"?
"somewhere in April"?
"sometime during April"?
something else?