The striker, who signed from Lokomotiv Moscow last Monday for £13.5million, did not have clearance to face Newcastle last week and was left out of the squad for the weekend's 3-0 win over Stoke after only completing one full training session.
Niasse, a 25-year-old Senegal international, has not played a competitive game since December.
Asked if Niasse's debut could come against the Baggies, Martinez told evertontv: " It could
He had one full session with the team before the Stoke game but I thought it was probably a bit too early.
"This week has been completely different, he has had a really good working period and all he needs is some good solid work before he can compete in the team.
"The Premier League is a competition that you have to be ready in order to have an impact.
"It is important he gets the time and the understanding he needs but, at the same time, I have seen he is desperate to be involved."
Source: PA