The club said its Premier League home game against Manchester United on January 13 will be played at Wembley.
It said: “The past few months have been spent rectifying issues with the critical safety systems.
“We are pleased to report that progress has been steady and we are now into the integrated testing and commissioning phases that take place ahead of the application for a stadium safety certificate.
“Testing is being conducted both during the day and night and our contractors will continue to work during the Christmas period.
“Barring no further significant issues we should then be in a position to schedule Test Events.
“This does mean therefore that we need to confirm that our Premier League home game against Manchester United will take place at Wembley.
“We shall receive a status report from our contractors in the week commencing 7 January 2019 and will update you thereafter.”
Chairman, Daniel Levy added: “We are acutely conscious that we are asking fans to go to Wembley for far longer than any of us wanted to. However we are now seeing the progress that we needed to see.
“What I don’t want to do is set any firm dates until we have finally achieved a safety certificate.
“So many people tell me to look at other major schemes that run late and, whilst I know it happens often, we are still hugely frustrated.
“It is important, however, to recognise the sheer complexity of the scheme.
“It will be one of the first fully-integrated digital stadiums and will also be required to meet the latest and most stringent safety regulations.”