only recently; just the other day
Emphasizes that something happened very recently, often with a sense of surprise or immediacy. Similar to 昨日今日, but the や adds a slightly more colloquial or emphatic feel.
See also: 昨日今日
昨日や今日始めたばかりなのに、もうこんなに上達したの？
You only started just recently, and you've already improved this much?
その話は昨日や今日のことではない。ずっと前から
That's not something I heard only recently. I've known about it for a long time.
Phrase composed of 昨日 (yesterday) + や (and/or) + 今日 (today), literally 'yesterday or today', used idiomatically to mean 'only recently'.