According to a user in a forum, it suggests to Apple fans to wait and stay tuned for May 2017 for the opening of the Retail Store which the user had indicated from the various posts in a thread that discusses in the upcoming Apple Retail Store in Singapore.
There is however no official comment or statement made by Apple, thus you may want to take it lightly on the rumoured opening date.
The initial date of completion was 31st October 2016 but was held back by 3 weeks in an order for works to be stopped. As works continues, the work notice indicated for another 3 months for completion till 31st January 2017. However, as soon as the date nears, the date has since been taped over suggesting in an unknown date in the opening of the Retail Store.
We will update you more when the Apple Retail Store in Singapore is going to open. Stay tuned to My Apple Singapore!