The Cowboys like to hold training camp out in Oxnard, CA to avoid the crippling Texas heat in July and August. So they generally spend close to a month out there and in the process squeeze in a couple of West Coast games before flying back to Valley Ranch for a couple of home games and more practice. But based on this year's preseason games and a concert by the boy band One Direction at AT&T Stadium, the Cowboys will likely cut short their time in Oxnard. The concert by One Direction falls in the third week of the preseason schedule, meaning the Cowboys usual practice of home dates for their third and fourth game will not work.
Last year, the Cowboys convened camp in Oxnard on Sunday, July 21st. But they were playing in the Hall of Fame game last year, which meant they got an early start. The CBA states:
Veteran players (defined as a player with at least one pension-credited season) other than quarterbacks or "injured players" (as defined in CBA Article 21, Section 6) may report to a club's preseason training camp no earlier than 15 days prior to the club's first scheduled preseason game or July 15, whichever is later.
The Cowboys first preseason game is scheduled for Aug 7-10, so if you take the 7th as the date, the earliest the full roster can be out in Oxnard is July 23rd. It could be as late as the 26th. The second game, the game against the Ravens will occur on Aug 14 - 18. The Cowboys will have to fly back to Dallas for that, then make the decision to return to Oxnard for another week then fly to Miami for the third game, or just stay at Valley Ranch after the Ravens game.
The Cowboys have yet to release their training camp schedule, but odds are that they will have a short camp in Oxnard and stay in the Metroplex after the Ravens game because the third preseason game is at Miami.
Per a source, the Cowboys had planned to return to Oxnard after the Ravens game, but that was before Wednesday's schedule release and the news they would be playing at Miami in Week 3. It doesn't make financial or logistical sense to fly from California to Miami.
So based on all of that, it sounds like the Cowboys will be in Oxnard for three weeks, possibly less.