The Ospreys currently head Pool 3 by four points from both Clermont and Leicester Tigers but have to face those same sides on the final two weekends of pool action.
And Jones knows that if his team want to become the first Welsh side to be crowned European Champions, then occasions like Saturday's trip to central France and the following week's home tie with the Tigers are absolutely crucial.
"We are at crunch-time now and you can't fail to be excited about it," said Jones.
"We've worked hard to put ourselves in a good position after four rounds, but this is where the hard work really starts.
"If we don't hit the right performance levels in the final two fixtures this month then the results we secured in October and December won't count for anything."
Despite his cautious approach to the last two group games of the season, Jones is confident that the 2008 and 2009 quarter-finalists have what it takes to reach the last eight for a third successive year.
Scott Johnson's side have recovered from a slow start to the season and are flying high in both their domestic league and on the European scene.
And Jones is determined to ensure that fine form continues as the region face two of their most important games in their short history.
"We realise that we face a tough challenge, but we have been working hard to build towards January as we always knew that this was the decisive month in terms of progression to the next stage," added Jones.
"We've improved throughout the season week on week, but we are under no illusions about where we are right now - we realise that we still have some way to go if we are going to finish off the job
"The focus is very much on continuing that improvement and raising all areas of our game to another level.
"We go out to Clermont Auvergne knowing that we have to be professional out there and do our job properly to ensure that we bring something back with us.
"If we can do that, it will then set up the Leicester game to be something special. There'll be a big crowd, just as there was up in Welford Road, and with it, there should be a great atmosphere.
"It's fantastic to be involved in big games like these for the region and everyone in the squad is looking forward to them."