England face Wales (twice) and Ireland before Johnson has to cut his squad down to just 30 for the global gathering in New Zealand and Stevens admits there is no room for complacency among the country's elite.
"I think the good thing at present is that the coaches have made it clear that every position is up for grabs," Stevens told the Daily Telegraph after the first week of England's training camp.
"There are no guarantees. It's up to the players to push themselves into the frame and make sure that when the plane leaves, they're on it.
"The training schedule has been particularly tough over the past few days and it's going to get even tougher. It's quite clear from what I've seen this week, that the coaches are stepping up the training in preparation for the warm-up games next month.
"I think the warm-up games will be key and, to be honest, we have already started speaking about Wales in terms of our training patterns."
As for Stevens himself, the Saracens tight-head is delighted to be back involved with his country but equally determined to make the final squad having been a replacement in the 2007 World Cup Final against his native South Africa.
The 2005 Lion has enjoyed a rapid rise back up the international ranks since his suspension came to an end in January of this year after he what he freely admits was a challenging time in his life.
"First and foremost, I'm glad to be back in the party and back with the guys alongside whom I have played so much rugby in the past," added Stevens.
"To spend two years away from the game you love playing is difficult. It was certainly not an easy time for me, but I remained positive throughout my break and kept my chin up as best I could.
"As far as returning to play, it was always my aim to give it one more go. Of course, it's far from easy to return after two years, but I have enjoyed every minute of the last six months. I am grateful to Saracens for giving me the chance and delighted that I am back here with England.
"However, I'm not going to settle for this. I want to earn a place at the World Cup and prove that I still have a great deal to offer."