A:Our new production control program's going live on Monday . The old and the new programs will operate in tandem for <MASK> . That should give us time to iron out any little problems . B: Hope it all goes well . We're very busy at the moment and certainly don't want any problems at this time of year . A: Yes , I realise that . We've spent a long time planning and preparing for the change-over . I'm confident we won't have any major problems .
four to six weeks four to six years four to six days