The authorized Leo constellation is to be about 7,700, on par with the 12,000 Starlink is authorized, but Starlink already has 10,000 in orbit compared to 250. At 50 a launch for easier math, to get to half the requested constellation, that's another 55 launches that are successful. Blue origin will be investigating for a while, and re-constructing for months. If the system works with just 1000 in orbit, that's still at least 15 launches before a system might be usable for business. Delta plans to install these to be used in 2028? Calling 2028 to mean end of December 2028, that's 30 months for at least 15 launches. The aircraft can be modified in that time, seems plausible, but what will they connect to, certainly not Leo unless they book a block of Falcon launches.