The interpretation of when the work to be applied for "Signatures completed by 4/30" is completed is left up to the applicant.
Completion" means "to be complete. To be completely finished." (Kojien), so it is up to the applicant to decide whether "completion" or "opening of the facility" should be considered as completion.
In either case, please make sure that you do not submit the same work twice, one for this year and the other for the following year.
If you are at a loss to judge, we suggest that you consider the date the work was "opened to the public".
If the opening has been extended and is not open to the public, you may consider the date of future opening as the "completion" date. On the other hand, in the case of offices, etc., there are cases where the building has been handed over to the business and the tenant is about to move in, etc. In this case, the date of completion and handover can be interpreted as "completion.
If the same building is completed on different dates in different areas, entries may be submitted for different years for different areas.