I think your redefinition of the word day is not scientific. The matter that formed the early Earth was likely orbiting the sun and rotating way before it was suitable for life. That means that a day was probably about 24 hours for the last 4 billion years or so. Even if the time called a day has changed, it would have been more accurate to measure it by today's standards. We know that higher life forms took several orders of magnitude more than a day to come about, therefore the Genesis account is scientifically inaccurate.