It is my understanding, that it is appropriate, upon hearing good news that benefits others, to recite the ha'tov ha'metiv blessing. As it's clear that you are absolutely stoked and excited about the completion of this huge project, congratulations and Mazel Tov!

Barukh attah Adonai eloheinu melekh ha-olam, hatov vehametiv.
(Blessed are You, L-rd G-d, King of the universe, who is good and who does good.)