When will the property be fully developed?

Well, it all adds up like that and in the end everything gets more expensive because the price quotes were, of course, all net prices, "because as a builder you have to understand that" (sic!). :-(

Yes, of course it gets more expensive because additional handover shafts / shut-off valves may need to be installed, the road has to be opened and closed again, and the distance is simply longer. Development is always something individual, the only help is: call local utility providers: inquire about prices, inquire about services (some providers offer earthworks, some don’t, some up to e.g. 12m, etc. etc.) Then you know what additional earthworks and pipe laying you need, which you can e.g. commission with your shell builder. This way you get a total sum, it will easily be five-figure. All providers charge at least 1000€ connection fee plus any preliminary information, connection permits, and final inspections; wastewater usually requires a tightness test or even camera inspection. Telekom/cable network operators may require the installation of special (and expensive) pull-wire conduits. Rainwater and wastewater handover shafts alone cost around 2-5000€ each if required. Well, it all adds up like that and in the end everything gets more expensive because the preliminary price information was of course all net, "because as a builder you have to understand that" (sic!). :-(

OT: this gross/net thing annoys me endlessly too. Yes, of course you eventually understand it, but sorry, as an end consumer you are simply used to gross prices your whole life. I'm even looking forward to asking whether net/gross when I think about it.

Is the road really going to be completely torn up and repaved? Sounds very expensive...