Defensive end Carlos Dunlap signed his six-year deal on July 15, 2013. There's a bit of a backstory here. Michael Johnson was designated with the franchise tag and the team had until July 15 to sign him to a long-term deal -- or else he'd be locked into the one-year contract.
When Johnson's camp reportedly rejected a $40 million deal over five years, the Bengals added a sixth year and handed Johnson's deal to Dunlap. Less than a year later, Johnson signed a five-year deal with Tampa Bay worth $43.75 million and $24 million guaranteed (he was seeing between $11-15 million guaranteed from Cincinnati).
Generally speaking, if the Bengals are going to sign a player to a significant extension, it's going to happen within the next two months. Currently linebacker Vontaze Burfict and quarterback Andy Dalton, both of whom are entering the final year of their respective deals, are favored to receive long-term extensions prior to the start of the 2014 regular season.
Call it a trend.
On August 31, 2011, the Bengals signed Andrew Whitworth to a five-year extension worth $30.4 million. Two days later, Cincinnati signed Leon Hall to a five-year deal worth $42.375 million. Former starting center Kyle Cook also signed a four-year extension on the same day. Then last year, the Bengals signed Geno Atkins to a six-year extension on September 2nd... two years after the team announced the extended trio from '11.
Could the evidence that Cincinnati will sign Dalton and Burfict in late August and early September be contained to 2011 and Geno Atkins in 2013?
Sadly, there isn't enough examples. Save for re-signing restricted free agents or free agents with expired contracts, the Bengals aren't exceptionally proactive about signing players to long-term deals. Domato Peko signed a five-year extension on June 12, 2008, after only two seasons in the NFL, on a deal worth $27.765 million. He would sign his second extension with Cincinnati on March 26, 2014, adding two more years to his existing deal.
Will the Bengals wait a week or two prior to the regular season? It makes sense, preventing possible distraction that will be inevitable for the regular season. But it's not necessarily the only window for it to happen. Keep your eyes open; it could happen at any time.