There are 255 sleeps (255 days) until July 5 (Monday, July 5, 2027).
There are 255 days until July 5 (Monday, July 5, 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 July 5. Sleeps are the same as days.
255 sleeps is 36 weeks and 3 sleeps.