Jenkins was expected to start on Monday in Baltimore, but a rainout this week in New York altered the club's plan. Tuesday's game against the Yankees was postpned, which pushed back Ricky Romero's start by one day.
Romero and Henderson Alvarez will start during a doubleheader in Baltimore on Monday, while Jenkins goes one day earlier.
"Right now, yes," manager John Farrell said when asked if he would stick with a six-man rotation going forward. "With Monday's doubleheader, we do have the need for six starters, so that's where we are."
Jenkins came up through the Blue Jays' system as a starter, but has spent the first 10 games of his career pitching out of the bullpen. He has allowed 10 runs in 18 1/3 innings while striking out eight and walking six.