Launched in Nov2022, TOP in 2029
The ones along Yishun Avenue 1 were launched in Nov2022 for sales, but those plots of land were full of trees. In other words, the land wasn't prepped for any kind of construction yet. I suspect, but can't confirm, that these are likely meant for sales launch in 2023-2024, but brought forward to 2022 because HDB wanted to say that they've a bunch of units for sales.
It takes around 1 year to flatten land for construction work. The projects were open for bidding on Gebiz by main cons only after the sales launch. One of them is my ex-company.
Launched in Oct2025, TOP in 2028
The Yishun Glade one is launched for sales in Oct2025. This site is already hoarded up, likely with main contractor already occuping the premises. That means a main con was already selected and started work before sales launch.
Simple. HDB launched for sales to public in Nov2022, but the Gebiz listing was only put up after that.