I'm not a Jehovah's Witness but I have read their March 2014 Awake! article 'The Untold Story of Creation' (see the link below). I also found this Awake! January 2014 article “Creation”: “God created the universe, including the earth, in the indefinite past—“in the beginning,” as Genesis 1:1 says. Modern science agrees that the universe had a beginning. A recent scientific model suggests it to be almost 14 billion years old.”
“The Bible also describes six “days” of creation. However, it does not say that these were 24-hour days. (Genesis 1:31) In fact, the Bible uses the word “day” to refer to various lengths of time. For example, it calls the entire period of creation “the day that Jehovah God made earth and heaven.”
The article continues: “The false ideas of creationists could lead you to dismiss the Bible altogether. On the other hand, if the Bible actually contains a credible account of creation, you stand to benefit from its storehouse of “practical wisdom.”
With regard to evolution, the article says: “Did God use evolution to create life on earth? The Bible does not specify how much variation can occur within a kind, as might result when animals within a kind interbreed and adapt to their environment. While some view such adaptations as a form of evolution, no new kind of life is produced. Modern research supports the idea that the basic categories of plants and animals have changed little over vast periods of time”.
I understand that the length of the seventh day, God's day of rest, is still understood by them to be 7,000 years long and that Adam was created in 4026 BCE. "Eight years from the autumn of 1967 would bring us to the autumn of 1975, fully 6,000 years into God’s seventh day, his rest day… the great sign of the ‘last days’ has been in the course of fulfilment since the beginning of the ‘time of the end’ in 1914. Some of the generation that discerned the beginning of the time of the end in 1914 will still be alive on earth to witness the end of this present wicked system of things at the battle of Armageddon.” (Watchtower 1 May 1968, pp 271-272)
Clearly, the length of the seventh "day" being 7,000 years long is critical to their expectations about the future.
P.S. Just to explain the difference between YOUNG Earth Creationists (YEC's) and OLD Earth Creationists (OEC's). Old Earth Creationism is an umbrella term used to describe biblical creationists who deny that the universe was created within the last 6,000 to 10,000 years over the course of six consecutive 24-hour days. Old Earth Creationists differ with Young Earth Creationists on the following:
1) The age of the universe. Young Earth Creationists believe that God created the universe 6,000-10,000 years ago. Old Earth Creationists place the creation event at approximately 13.7 billion years ago, thus being more in line with “mainstream” science, at least on this point.
2) The time of the creation of Adam and Eve. Young Earth Creationists place the creation of Adam no later than 10,000 years ago. Old Earth Creationists are varied on this point with estimates ranging somewhere between 30,000-70,000 thousand years ago.
According to that Awake article (see link below) that means Jehovah's Witnesses are OLD Earth Creationists because they think the universe and the Earth are billions of years old. However, they also say Adam was created less than 10,000 years ago, so that puts them in the YOUNG Earth Creationist camp! At least Jehovahs' Witnesses are Creationists, which is good.