Harry had said it, heard it and thought it about 12 dozen times since they first found out about the Death Eater attack - they were ready for this. He was definitely ready and had been waiting impatiently all day. Then the time had come and it seemed like he had hardly been waiting at all.
Dumbledore's Army, the Order and some of the Ministry arrived just in time as the Death Eaters appeared inside the DMLE. He didn't hesitate to get right into the middle of it, making sure that everyone around him looked they were holding up, Harry shot multiple curses at two Death Eaters heading in his direction and watched one go down as the other kept coming.
Ducking a flying hex from the cloaked one he missed, Harry quickly shot another curse at him and then looked around for Ginny, just as he'd promised Ron. She looked a bit shaken but ok, and he looked around again to find Ron and Hermione, who he could see were in battles of their own. As he continued his surveying, some of the Death Eaters looked like they were retreating and there were also a number of them down on the ground. Harry didn't want to look too closely however, just in case down there was some of their own.