Why the end of the period is the best moment for your enquiry.
Publication starts the public consultation period (20 or 30 days depending on the canton). During that time the plans are publicly available and those affected can object.
If the period passes without objections, the path to approval is usually clear — the project will very probably be built. For you that means: this is when an enquiry to the building owner is worth most. The project is secured, but marketing has not started.
Objections delay, but rarely prevent altogether. Large projects are often approved in an adapted form. Stay with it by watching the project — we report every change of status.
On every project page the objection period appears in the timeline; with "Notify me of changes" you will not miss the end of the period.