Edinburgh Zoo's panda keepers are monitoring Tian Tian around the clock.
Experts are not certain if the panda is pregnant but the latest hormone tests are said to show positive signs and she is now being closely watched for signs of labour such as restless behaviour and bleating.
She could give birth any time in the next two weeks, according to experts.
The birth itself could last only a matter of minutes due to the small size of newborn cubs, which weigh just 100g.
Iain Valentine, director of giant pandas for the Royal Zoological Society of Scotland, said: "We have now entered the window of the possible time that Tian Tian could give birth.
"Keepers are monitoring Tian Tian on a 24-hour basis. They are able to log in from their computers and phones at home just to make sure everything is ok with her, and a keeper from China has now arrived to support us. We are ready.
"About 24 hours before she gives birth she will become quite restless, start moving around, and then will sit down, her waters will break and then quite soon after that she will give birth.
"The birth process can be over quite quickly because the cub itself is very small. It could take minutes. It is down to the timing and her being comfortable. The cub is only 100g, so she doesn't have to strain too much to give birth."
Tian Tian and her male companion Yang Guang arrived at Edinburgh Zoo in December 2011 after a 5000-mile flight from China, becoming the first giant pandas in the UK for 17 years.