Waterway Sunrise 1 & 2 consist of two empty pieces of land just cleared of vegetation ( trees and shrubs ) a couple of weeks ago.
Next will be the putting up of signboards by both the Civil Engineering Contractors / HDB of the intending projects. Second : construction of temporary offices and material stores. Third : Moving of Heavy piling machineries, cranes, tractors and so on.
Piling alone will easily take about 3 to 4 months.
Roughly base on past Punggol Building projects from starting to completion and final TOP should be plus / minus 4 years. Your estimation is correct