Six literal days is the only thing I read from the Bible.
However, I'm not sure that we know exactly long the days were at that point in time. The Bible is clear on morning and evening, so six rotations of the earth, but could the earth's rotation time be different than today?
Because of these questions, I can't say I believe in "young earth" for certain. It could very well be, and I'm open to that. Yet I won't dismiss the possibility the earth could be older.
The earth was created, and we are clearly using morning/evenings as the basis for time keeping, that means we must use the earth itself as the reference frame for time.
The earth could have rotated faster, or slower. Creation could have happened in 6 seconds, or 6 years. I am only certain that we had six days/nights.
Does the amount of time God took to create things matter? I'm not sure. It would be interesting to know, but I am kind of nervous about speculating on this topic.
God did what he pleased during creation. I think of Job, where god says:
Job 38:4-6
"Where were you when I laid the foundation of the earth?
Tell Me, if you have understanding,
Who set its measurements? Since you know.
Or who stretched the line on it?
"On what were its bases sunk?
Or who laid its cornerstone,