Based on responses, I'm noticing a trend of people hearing back exactly 14 full days after they apply.
So for example, the initial deadline before the rolling period began was April 15th and several respondents heard on April 30th. The first date to count is the 16th(the first full day after the deadline), so the 16th to the 30th: exactly 14 days.
Someone applied on May 28th and got an interview on June 12th, which is exactly 14 days if you start counting on May 29th (the first full day after they applied).
Someone else applied on the June 1st deadline and got rejected on June 16th, again exactly 14 days if you start counting on June 2nd (the first full date after they applied).