The Baggies, who were being watched by chairman Li Piyue and his wife, scored three goals in an 18-minute blitz in the first half to beat Tony Mowbray's Blackburn side 3-2.
Matt Phillips, Jake Livermore and Grady Diangana all found the net for Albion, who remain unbeaten after six games with 12 points on the board.
"I am pleased, first home win," smiled Bilic. "We have an international break now, it's great. We've just finished the first cycle from June. We went to Spain, hard training and all that sweat.
"Six games unbeaten, first home win, and now we have a few days off to recover physically but more than that, mentally. It's a good feeling really."
Bilic was rewarded for handing Matheus Pereira his first league start, because the Brazilian set up the first two goals and was an influential figure in the first half.
But the Croatian is confident his side, who gifted Blackburn two goals and one after just 25 seconds, will continue to improve after the hiatus.
"We are a new team, we are still gelling, we still have those phases where we can improve," he said.
"If you are sterile it is difficult to improve but we are not that. It makes me happy because those things we are showing, not consistently throughout 90 minutes, we can get better.
"We can't even talk about slow start, we didn't even start, straight away it's a goal. Especially at home the crowd is expecting to win, it affects the team psychologically.
"Blackburn smelt it and were on top of us, in those moments we need something. We scored a great goal, great combination, from then until the end of the half it was top football in every aspect of the game, creating chances, defending well, pressed them well.
"We stopped them in our half. It's stupid to say, it sounds greedy, it should have been even more than 3-1. But 3-1 should be enough.
"That happened with our second goal, set piece. I had a feeling it was a small foul on our player, and a mistake from us.
"We knew they would come back fired up and they were, credit to them in the first 15 minutes we were playing like it was added time.
"I said at half time 'it's 0-0, play a normal game', but we were happy to waste time a little bit, we weren't active, we weren't on the front foot.
"They were in our half of the pitch but after 15 minutes we gained control and created chances to kill the game off but our shooting was not good enough.
"There's always a danger that you concede a goal, they have good players. We didn't survive, we managed the game well. So of course we are happy."
Former Albion boss Tony Mowbray was frustrated the referee ruled out a third goal for Blackburn in the second half for a foul on Sam Johnstone, but he believes his old team will be strong this season.
"I think for half an hour in the first half, they were very good," admitted Mowbray. "I thought for long spells in the second half, especially the first 25 minutes we were on top but couldn't get the goal.
"Having watched back Bradley Dack's goal, I'm not sure the referee can see it, he's looking through nine men. Frustration that he played safe and gave a free-kick.
"Stewart Downing had a shot that scraped the post, we could have come away with a point but I think Albion are a good team, they showed that in the first half. Albion moved the ball well and they'll have a strong season."
Blackburn were fortunate to be just one goal behind at half-time, having been gifted two by Albion errors, but they were much improved after the break.
When Mowbray was asked what changed at half-time, he said: "We had to be brave with the ball, we had to be dominant with the ball.
"Second half we kept it for much longer, they couldn't hurt us as much. Sometime the best form of defence is attack and possession. I think we took the sting out of them second half. We didn't allow them to build up momentum. We tried to play our own game better."