Pakistan too was to celebrate Independence Day on Aug 15!

Mohammad Ali Jinnah, Pakistan's founder and first Governor-General, declared August 15 as the country's Independence Day but the authorities advanced it by a day in 1948 as it fell on an auspicious day of Ramzan.
"August 15 is the birthday of the independent and sovereign state of Pakistan. It marks the fulfilment of the destiny of the Muslim nation which made great sacrifices...," Jinnah said in his first broadcast to the nation in 1947.
Pakistan decided to advance the Independence Day celebrations by a day in 1948 to August 14 as it coincided that year with Shab-e-Qadr or the 27th day of the holy month of Ramzan. This day is considered most special by the faithful and the night is spent in prayers.

In the years that followed, Pakistan continued to celebrate its Independence Day on August 14. The country celebrated its 67th Independence Day yesterday.
Yasser Latif Hamdani, a Lahore-based lawyer and author of "Jinnah: Myth and Reality", told PTI: "Pakistan was to celebrate its Independence Day on August 15 but because of Shab-e-Qadr it was advanced by a day in 1948. However, it stuck to its mistake and continued to celebrate following Independence Days on August 14 too."
Hamdani said it couldn't have been Jinnah who changed the date to August 14, because by that date in 1948 he was already on his deathbed.

However, he insisted the change of date was deliberate as Pakistan was a new nation and needed to carve an identity.

Jinnah's daughter Dina Wadia's birthday too was on August 15.
As the power of transfer from the British took place on the midnight of 14 and 15 August, the Indian Independence Act, 1947 stated that August 15 was the birthday of both Pakistan and India.
"As from the fifteenth day of August, nineteen hundred and forty-seven, two independent Dominions shall be set up in India, to be known respectively as India and Pakistan," the Act reads.
Pakistan's first commemorative postage stamp released a year later also mentions August 15, 1947 as the country's Independence Day.