Inquiry about transfer of ownership vs. building application

we had it like that too. you receive a letter from the notary with the request to transfer the full purchase price. with this transfer (cut-off date) you then become the contractual owner of the property with all rights and obligations (e.g. property tax etc.). the construction notification was also processed for us at the same time (+-3 days), so that we started directly less than a week after payment. the complete registration in the land register then somehow takes place around the move-in time. we bought directly from an investor, the notary handled all properties in the area and no one had any problems. the final registration also took longer because everyone was a bit overwhelmed by the huge new development area... a pure construction time from the foundation of 6-7 months is ambitious and in my experience here in the development area is only achieved by well-organized companies with high own contribution or always the same subcontractors with external planning through the construction company. Viebrockhaus guarantees 3 months for example and has managed it in the constructions in the neighborhood (+2 weeks Christmas vacation).