There's no secret, it's just that many schools do not publish their interview dates (some do, look on their websites). Program directors may opt to move the interview dates as they see fit from year to year, but in general it should be similar to last year. Just keep an eye on this page since it was very helpful for me during my application process.
I highly doubt there are any interviews happening right now because the programs are busy graduating their outgoing class. Then they have to onboard their new class for a week or two. Then they will interview for next year's class... so early July at the earliest.