The Baggies travel to take on David Moyes’ side in the fourth round of the competition in 11 days’ time.
Bilic is eager to progress as far as possible with the 51-year-old a big fan of the world’s oldest cup competition.
But the boss feels his team’s hectic Championship schedule is forcing him into resting players to ensure they don’t get injured.
Albion travel to take on Cardiff just three days after their trip to the London Stadium.
They then have to play seven games in February, with that increasing to eight if they beat the Hammers.
“The FA Cup is the thing that is strange,” Bilic said when asked if fatigue will play a part in the race for promotion.
“On one hand you want to progress, and it’s good to have that game for the guys who haven’t been playing or if you want to make a mix.
“The problem is that game you were supposed to play.
“You are talking about tough fixtures, it’s really tight and there is no break.
“Now, instead of playing Cardiff on January 25 we have to play them on January 28 when we already have seven games in February.
“Then, if we go through against West Ham we are in double trouble. Seriously, what do you do? They are basically forcing you to give up.
“There are so many games and fatigue is a major thing. Fatigue can become injury.
“You have to manage the players, if you are suddenly without five players it’s difficult.
“One player makes a difference, let alone three or five, and that’s why so many games make a difference.”
With the Championship being such a demanding league, Bilic says it’s hard for managers to be able to plan when they can rest players.
“It’s very difficult to do that (plan),” he continued. “We know that in three weeks we play Sunday-Wednesday-Saturday (Millwall, Reading, Nottingham Forest).
“And Saturday is a 12.30 kick-off so it’s less than six days for three games.
“That is in three weeks but how can we think about that now?
“It’s impossible. You know that it’s coming but you can’t do anything because every game is important.
“You are thinking more between the games about how you’re going to manage them.
“I think one of the reasons why we’ve been good this season is that we didn’t use 11 or 12 players so far.
“That’s why I never talk about a first XI but about 15 or 16 players.
“Some have played more and some less but you are calling them regulars.
“That changes every five or six weeks, somebody can come in and somebody can drop out, but it’s not 11, it’s 15 or 16 players.”
Bilic says having no international breaks at the turn of the year also makes it more likely managers will rest players in the FA Cup. “Don’t forget in the first half of the season, we had three international breaks,” he continued.
“Every month we had a couple of weeks off and no team has more than five or six international players, so the majority of the squad stays here and you can make a conscious effort to rest them from the games they’ve done and prepare them for the next one.
“We had that privilege three times so far and now we have it just once, at the end of March.”
Despite the hectic nature of English football, Bilic wouldn’t change it. “It’s been a long issue,” he said when asked if the season needs amending.
“When I was in the Premier League we used to have those meetings but they’re not changing it.
“You can’t be hypocritical and that’s one of the reasons why these leagues are so popular and why the Premier League is the Premier League and the Championship is the Championship of the Championships.
“That’s why it’s so attractive for so many players from abroad to come here.
“It is because of the specific number of games or TV rights and to get that we probably have to play so many games.
“All of us would love a little bit of a break for New Year but it’s not like that here.
“There’s no point moaning about it.
“You just have to cope with it and be ready for it.”