Authorities said Kai Kai and Jia Jia may now only set foot in Singapore at the end of the year.
The two are in good shape and are getting ready for their stint together in Singapore.
Kai Kai and Jia Jia's enclosures have been placed side by side, so they can get used to each other's smell.
But the final details of their migration and their new homes are still being worked out.
Li Desheng, director at Sichuan Wolong Nature Reserve Administration, said: "For instance, (details include) where the surveillance camera is placed, the height of the panda weighing machine. The control of the emergency exit is crucial because the zoo keepers have to enter to clean the enclosure and train the pandas. The pandas may behave violently when they are unhappy."
The duo are on a 10-year loan to foster good ties between China and Singapore.
Claire Chiang, chairwoman of Wildlife Reserves Singapore, said: "There are details that deal with the air conditioning, the lighting, the planting etc. I think we've met all the conditions. What we hope to do is to be sure that the entire precinct around the panda will be in the best state when they come."
And Singapore's Minister of State for Trade and Industry, Teo Ser Luck, who's visiting the pair in Chengdu, said it's important that they're well taken care of.
Mr Teo said: "I think if it takes a longer amount of time to get prepared and to learn their skill sets and the knowledge, I think we should (wait). We should take that time because at the end of the day, this is a national treasure of China and we have to take it very seriously. We have an even heavier responsibility to make sure the pandas are in good hands."
The China Wildlife Conservation Association is planning to make a fourth trip to Singapore sometime in July.
A date will only be set after they have made sure all the modifications are done and everything is in order.
Both Singapore and China are hoping the Giant Pandas can fly to Singapore by the end of the year.
After arriving in Singapore, the pandas need another two months for quarantine and conditioning to the new environment.
