"My mindset going into the game is you play in the game until they tell you to come out," Gabbert said. "You can't go into any game thinking you're only going to play a couple series or quarter because if you play longer, you're not going to be prepared."

The quarterback explained that he's excited by the progress the offense has made since the start of the offseason program back in April. Each position group understands the play installs and is now working to thrive in Kelly's offense.

Gabbert has dominated the first-team reps since the first days of Organized Team Activities. A trio of offseason surgeries and a fatigued throwing shoulder has kept Colin Kaepernick sidelined for a bulk of the 49ers ongoing quarterback competition.

That could change on Friday as Kaepernick is expected to make his 2016 preseason debut. Kaepernick has been full-go at practice this week, and the first-team practice reps were once again split down the middle between the two signal-callers.

Gabbert doesn't know if his number will be called on San Francisco's opening possession, but the quarterback understands what will be expected of him when he does take the field.