There are 300 sleeps (300 days) until August 19 (Thursday, August 19, 2027).
There are 300 days until August 19 (Thursday, August 19, 2027) — one sleep per night.
One sleep per night between now and the big day — tonight is the first sleep, and the morning after the last sleep is August 19. Sleeps are the same as days.
300 sleeps is 42 weeks and 6 sleeps.