The Gunners started the season with two defeats from their first three top-flight outings, going down by an aggregate 5-0 scoreline to Stoke City and Liverpool.
After seeing his side get back on track somewhat with victory over Bournemouth and a well-earned point away at Chelsea, on top of wins in the EFL Cup and Europa League, Bellerin acknowledges the importance of adding three more points to the board against Albion on Monday night.
"It is all about keeping the momentum going," he told Sky Sports News. "In the League Cup, even though the team completely changed, I think the mood in the whole squad was the same. Everyone came out on the pitch to get the win and we have to keep building on this momentum right now and make it another win for us hopefully.
"Even before Chelsea, the games against Bournemouth and in the Europa League helped the team build up the momentum. And the last few games against Chelsea, we have always come out on top and the team was confident we could do the same again. We were a bit disappointed as we had chances to score and when you come out of the game thinking, 'we could have won that', it is a bit disappointing.
"But to perform away from Stamford Bridge, which is always hard, and to come out with a clean sheet and a solid performance was very good for the mood in the team and the club.
"We have to go game by game and just like at the beginning of the season when things did not work out too well, and now things are getting better.But we do not have to think that everything is now done, or the other way round. We have to keep working hard and keep getting these results now."
Arsenal follow up their clash against West Brom with games against BATE Borisov and Brighton & Hove Albion ahead of the international break.